Professional competency is widely recognized as a foundational determinant of service quality and ethical practice in school counseling ( Kaslow, 2004; Remley & Herlihy, 2010). As educational systems worldwide increasingly emphasize accountability, evidence-based intervention, and student well-being, the role of school counselors has expanded beyond traditional guidance functions toward comprehensive developmental, preventive, and systemic responsibilities ( Yuwono & Utomo, 2023; Zabek et al., 2023). In this context, the measurement of professional competency becomes not merely evaluative but strategic informing supervision, professional development, certification, and policy implementation ( Borders, 2014; Stolenberg & McNeill, 2010).

The construct of professional competency in school counseling is inherently complex and theoretically multidimensional. Regulatory frameworks, such as national counseling standards and professional accreditation systems, emphasize core domains including needs assessment, guidance and counseling program planning, service implementation, and guidance and counseling program evaluation ( Permendikbud No. 111, 2014). In the Indonesian context, for instance, the Regulation of the Minister of Education and Culture No. 111/2014 formally articulates four central competencies: (1) assessment of student potential, characteristics, and environment, (2) development of counseling programs, (3) implementation of guidance and counseling services, and (4) evaluation of guidance and counseling program. These domains represent the operational foundation of professional practice.

However, contemporary scholarship argues that professional competency extends beyond technical-programmatic capabilities. The literature emphasizes the importance of supervisory competency, continuous professional self-development, ethical accountability, and systemic collaboration within the broader educational ecosystem ( Kivlighan, 2008; Luke & Bernard, 2006; Riggs & Bartholomaeus, 2016; Vivekananda et al., 2021). Notably, three dimensions frequently underrepresented in Western measurement models include: (a) the supervision of pre-service counselor training ( Littrell et al., 1976; Luke & Bernard, 2006), (b) sustained personal and professional growth ( Stoll et al., 2006; Young et al., 2011), and (c) active collaboration with school personnel in co-curricular and systemic initiatives ( Yudha et al., 2024; Zabek et al., 2023). These dimensions are critical for sustaining the profession, ensuring service quality, and integrating counselors into formal educational structures ( Kaslow, 2004; Rice & Furr, 2013). Their inclusion reflects a more holistic and sustainability-oriented conception of professional competency.

Despite the acknowledged multidimensionality of professional competency, existing measurement instruments reveal several limitations. First, many instruments are fragmented, assessing isolated domains rather than an integrated competency system ( Ridley et al., 2021). Second, numerous tools are grounded in Western-centric professional frameworks that may not fully capture the regulatory and systemic realities of school counseling in emerging educational contexts ( Khairun, Taufiq, Yustiana, Budiman, & Al Hakim, 2025a; Khairun, Taufiq, Yustiana, Budiman, & Hakim, 2025b). Third, classical test theory (CTT) approaches continue to dominate validation procedures, often limiting measurement precision and failing to provide invariant item calibration across varying respondent ability levels ( Sumintono & Widhiarso, 2015). Consequently, there remains a need for a psychometrically robust, multidimensional instrument that integrates regulatory foundations with contemporary theoretical advancements while employing modern measurement models.

The Rasch Measurement Model offers a rigorous alternative to traditional CTT-based validation ( Bond, 2015; Boone et al., 2013; Sumintono & Widhiarso, 2015). By transforming ordinal raw scores into interval-level measures, Rasch analysis enables objective calibration of item difficulty and respondent ability on a common metric ( Linacre, 2016; Sumintono & Widhiarso, 2015). Furthermore, Rasch-based principal component analysis of residuals provides empirical evidence of dimensional structure, ensuring that theoretically multidimensional frameworks cohere into a unified latent construct ( Boone et al., 2013; Zaporozhets et al., 2015). This approach enhances measurement precision, supports invariance, and strengthens interpretability in applied professional contexts.

Grounded in both regulatory mandates and international theoretical perspectives, the present study develops a multidimensional Professional Competency Instrument for School Counselors comprising seven integrated domains: assessment, development of guidance and counseling program, implementation of guidance and counseling services, evaluation of guidance and counseling program, supervision of pre-service counselor training, continuous professional development, and collaborative engagement in co-curricular programs ( Luke & Bernard, 2006; Permendikbud No. 111, 2014; Stoll et al., 2006). Although theoretically multidimensional, these domains are conceptualized as interrelated components of a single overarching construct professional competency in school counselors.

Although previous research has examined components of counselor competency and professional identity, existing instruments tend to assess fragmented skill sets or remain anchored in narrowly defined programmatic domains ( Khairun, Taufiq, Yustiana, Budiman, & Al Hakim, 2025a; Khairun, Taufiq, Yustiana, Budiman, & Hakim, 2025b; Ridley et al., 2021). Moreover, competency models frequently underrepresent supervisory engagement, sustained professional development, and systemic collaboration domains that are increasingly recognized as essential to the sustainability and institutional integration of school counseling practice ( Luke & Bernard, 2006; Stoll et al., 2006; Vivekananda et al., 2021). Methodologically, many prior validation studies rely predominantly on classical test theory, which does not ensure invariant measurement or hierarchical calibration of item difficulty across varying respondent ability levels ( Sumintono & Widhiarso, 2015). By integrating regulatory competency mandates with expanded theoretical domains into a unified seven-domain framework and validating the construct using the Rasch Measurement Model, the present study advances both the conceptual architecture and the psychometric rigor of professional competency measurement in school counselors. This dual advancement strengthens the coherence, precision, and applicability of competency assessment within contemporary educational systems.

Accordingly, this study aims to develop and rigorously validate a multidimensional instrument for measuring professional competency in school counselors using a five-point Likert rating scale and Rasch Measurement Model analysis. Specifically, the study seeks to (1) evaluate rating scale functioning across ordered response categories, (2) examine construct validity through principal component analysis of residuals to establish empirical unidimensionality, (3) assess item fit and hierarchical item calibration, and (4) determine person and item reliability as well as separation indices to ensure measurement precision and internal consistency. By integrating regulatory competency mandates with expanded theoretical domains into a Rasch-calibrated measurement framework, this study advances both the conceptual coherence and psychometric robustness of professional competency assessment in school counselors.

This study advances the measurement of professional competency in school counselors by integrating regulatory mandates and contemporary theoretical expansions into a Rasch-calibrated framework. Although the instrument was theoretically structured across seven domains, Rasch principal component analysis of residuals demonstrated a dominant latent construct, with variance explained exceeding recommended criteria and first-contrast residual variance well below critical thresholds ( Boone et al., 2013; Sumintono & Widhiarso, 2015). These findings provide empirical support for the argument that professional competency, while conceptually multidimensional, operates as an integrated and hierarchically organized capability in applied educational settings ( Bernard & Goodyear, 2014; Kaslow, 2004).

The hierarchical ordering of item difficulty offers substantive theoretical insight. Foundational practices such as routine assessment and implementation of counseling services were positioned at lower logit levels, whereas supervision of trainees, engagement in research and scholarly production, and leadership within professional communities were located at higher levels. This ordering aligns with competency-based supervision frameworks that conceptualize professional growth as developmental progression from operational proficiency toward reflective, supervisory, and systemic expertise ( Bernard & Goodyear, 2019; Borders, 2014, 2019). It also reinforces the view that sustainable professional competency requires more than technical service delivery, encompassing mentorship, reflective practice, and institutional collaboration ( Luke & Bernard, 2006; Stoll et al., 2006).

Methodologically, the study contributes by moving beyond classical test theory approaches that dominate competency measurement research. While classical procedures remain useful for internal consistency estimation, they do not ensure invariant item calibration or interval-level scaling ( Bond, 2015; Boone et al., 2013; Sumintono & Widhiarso, 2015). By employing the Rasch Rating Scale Model, this study establishes item and person parameters on a shared metric, enabling objective measurement independent of sample-specific score distributions. The ordered category thresholds and satisfactory separation indices further confirm that the instrument meaningfully differentiates multiple strata of professional competency, strengthening interpretability for supervision and policy applications ( Bond, 2015; Boone et al., 2013).

The inclusion of supervision of trainees, continuous professional development, and collaborative engagement extends traditional regulatory frameworks that often prioritize programmatic implementation alone. Contemporary scholarship increasingly emphasizes that professional competency must incorporate supervisory alliance, reflective capacity, and systemic integration within educational ecosystems ( Bernard & Goodyear, 2019; Borders, 2014; Luke & Bernard, 2006). By empirically demonstrating that these domains function as higher-order indicators within a unified competency continuum, the present study provides evidence for a more holistic and sustainability-oriented model of counselor professionalism ( Kaslow, 2004; Stoll et al., 2006).

The novelty of this work lies in three interrelated contributions. First, it operationalizes a regulatory-theoretical synthesis into a coherent measurement architecture rather than assessing fragmented skill domains. Second, it empirically demonstrates hierarchical integration of advanced professional roles within a single latent construct. Third, it applies Rasch modeling to establish interval-level measurement and hierarchical calibration, thereby strengthening the precision and policy relevance of competency assessment ( Bond, 2015; Boone et al., 2013; Sumintono & Widhiarso, 2015). In doing so, the study responds to calls for more rigorous, competency-based supervision research grounded in robust psychometric methodology ( Bernard & Goodyear, 2019; Borders, 2019).

Several limitations warrant consideration. The cross-sectional design and moderate sample size limit generalizability, although Rasch estimation remains stable within this range ( Sumintono & Widhiarso, 2015). Self-reported frequency measures may introduce response bias, and future research should incorporate multi-source or performance-based assessments. Further analysis of differential item functioning and longitudinal sensitivity would strengthen evidence of invariance and developmental responsiveness ( Bond, 2015; Boone et al., 2013).

Overall, the findings position this instrument as a theoretically integrative and psychometrically rigorous tool for professional supervision, development planning, and policy evaluation within school counseling systems. By demonstrating hierarchical coherence and measurement precision within a unified competence framework, the study contributes both conceptual clarification and methodological advancement to the field of counselor education and supervision ( Bernard & Goodyear, 2019; Borders, 2014; Kaslow, 2004).

This study developed and Rasch-validated a multidimensional instrument for measuring professional competency in school counselors. The findings demonstrate strong structural validity, coherent hierarchical calibration, appropriate rating scale functioning, and robust reliability and separation indices. Although conceptually organized into seven domains, the instrument operates empirically as a unified latent construct, supporting the interpretation of professional competency as an integrated and hierarchically structured capability rather than a collection of isolated skills.

The calibrated item hierarchy indicates that foundational counseling practices represent core competence, while supervision, scholarly engagement, and systemic collaboration function as advanced indicators of professional maturity. This structure provides a scalable framework for assessing developmental progression within the profession.

Beyond psychometric robustness, the instrument offers practical utility for informing supervision systems, professional development pathways, certification benchmarks, and policy evaluation. With further cross-context validation and longitudinal testing, it has the potential to serve as a standardized reference model for competency-based school counseling systems at both national and international levels.

The authors wish to express their highest appreciation and profound gratitude to the Ministry of Finance of the Republic of Indonesia, through the Indonesia Endowment Fund for Education (LPDP), as well as to the Ministry of Higher Education, Science, and Technology of the Republic of Indonesia, through the Center for Higher Education Funding and Assessment (PPAPT) and the Indonesian Education Scholarship (BPI) program, for the financial support, facilitation, and sponsorship provided throughout the publication process of this research.

This study was conducted in accordance with international ethical standards for research involving human subjects. Ethical approval was formally granted by the Research Ethics Committee of Universitas Pendidikan Indonesia (Approval Nos. 9403/UN40.A1.1/TD.07/2024 and 1391/UN40.A1.07/2025). The initial approval was valid from 1 September 2024 to 31 January 2025 and was subsequently renewed for the period from 1 February 2025 to 31 August 2025. Data collection commenced on 2 February 2025, fully within the validity period of the renewed ethical approval. Participation was voluntary and anonymous, and all data were treated confidentially and used solely for research purposes.