The authors of 3 articles in this issue have collaborated in an effort to advance the conceptualization and measurement of participation. These articles offer (1) a new tool for measuring participation, the Participation Assessment with Recombined Tools-Objective (PART-O), which combines items from widely used instruments in traumatic brain injury rehabilitation research; (2) 2 methods of scoring 17 items of PART-O, assessing relatively objective social role performance and yielding 3 subscale scores, as well as 2 alternative total scores (including 1 incorporating the concept of balance among types of participation), and (3) 19 enfranchisement items assessing the degree to which people with disability perceive they have the freedom to engage in social roles of their choosing while being accepted and valued by others.