Purpose/Objective: The purpose of this study was to evaluate the psychometric properties of 2 novel measures assessing personal advocacy, self-efficacy and personal advocacy activities in individuals with acquired brain injury (ABI). Design: This was an instrument development study using (a) expert panel review with a content validity index, (b) consumer survey, and (c) Rasch analysis. Participants were adults (N = 162) with ABI recruited through a community survey. Main Outcome Measure: Participants completed the Self-Advocacy Scale (SAS) and the Personal Advocacy Activity Scale (PAAS). Results: Using Rasch analysis to inform instrument development, after modification on the basis of item response theory analysis, the SAS, a measure of advocacy self-efficacy, was found to be unidimensional with an eigenvalue of 1.6, exhibited monotonicity, and had an item reliability of 0.97. Similarly, the PAAS, a measure of advocacy activity, was found to exhibit monotonicity, is unidimensional (eigenvalue of 1.7) and had an item reliability of 0.97. Both measures demonstrated concurrent validity, because they were significantly correlated with other established measures of related constructs and with each other. A separation reliability of 0.97 (real not model) for both the SAS and PAAS suggests that items will likely hold their relative positions in a similar sample. Conclusions: This study supported the PAAS and the SAS as reliable and valid measures of personal advocacy activity and associated self-efficacy in individuals post-ABI.