The lack of patient reported outcome measures (PROMs) appropriate for youth with neurodevelopmental disabilities (DD) and related cognitive impairments including Down syndrome (DS) poses a significant problem for healthcare research and practice. Parents and other professionals do not identify the same needs as youth, and failure to engage youth with DD in healthcare evaluation compromises healthcare quality and outcomes. The market demand for a PROM for this population is high given the prevalence of DD and the significant healthcare costs for this population, of which the largest proportion with a genetic etiology is DS. In Phase I, we demonstrated that our technology can help youth with DD and related cognitive impairments complete PROMs. The PEDI-PRO prototype demonstrated strong internal reliability and elicited consistent scores from 56 youth ages 14-22 with DD and cognitive impairments. In fact, the Phase I award demonstrated ease-of-use of the survey in youth with an IQ range of 47-75 (of which 14% of the sample had DS), and the test-retest reliability and internal validity in those with an IQ range of 30-110 (of which 12.7% had DS). Clinicians across the country (n =14) established the usability of the PEDI-PRO prototype. This Phase II STTR will build a clinically robust PEDI-PRO Assessment Software to address the market gap in PROMs for youth with DD including DS. Specific aims: 1) Transform the Phase I PEDI-PRO concept prototype into a robust, fully functioning assessment software system for use in rehabilitation. 2) Test and optimize the psychometric properties of the PEDI-PRO item bank to ensure valid and reliable measurement. 3) Design a clinically interpretable score report that accurately characterizes youth’s functional performance. The Phase II study design adheres to the Consensus-based Standards for the Selection of Measurement Instruments (COSMIN) framework to establish the validity and reliability of the PEDI-PRO. We will continue our partnership with a Youth Panel (n = 5) and Advisory Board (n = 8). We will design the PEDI-PRO Clinical Management System (PCMS: a HIPPA compliant clinician administrative dashboard) and incorporate 45 additional items (15 per domain, selected by the Youth Panel and Advisory Board) into the PEDI-PRO. Second, 300 youth with DD will complete the PEDI-PRO, including 50 individuals with DS, thus exceeding the prevalence estimates that individuals with DS make up 15-20% of those with an intellectual disability. We will adhere to COSMIN standards and examine the structural validity and internal reliability using both classical test theory (CTT) and item response theory (IRT). We will also use hypothesis testing to establish known groups and convergent validity. Third, we will incorporate automatic scoring into the PEDI-PRO Assessment Software; we will use a mixed methods to design and evaluate two score report prototypes. This Phase II will enable AbleLink Technologies to aggressively pursue commerc...