Abstract
This study developed a Computerized Adaptive Test (CAT) and conducted a comprehensive psychometric analysis using Item Response Theory (IRT) to assess the knowledge of master's-level counseling students in Human Growth and Development, a core domain of the Counselor Preparation Comprehensive Examination (CPCE). A total of 775 participants were divided into six subgroups, each completing a unique set of 21 items from a 126-item pool. Items were calibrated using the 2PL IRT model, and the resulting parameters were implemented in the CAT via Concerto. The psychometric evaluation examined unidimensionality, local independence, monotonicity, and measurement invariance assumptions. Validity and reliability of the item pool were assessed, and fairness was evaluated through Differential Item Functioning. Results supported the use of the 2PL model, demonstrating well-distributed item difficulties and acceptable discrimination for most items. Limitations and future research directions were discussed.