Youth programs that are organized around intellectually challenging, socially relevant projects create opportunities for deep cognitive engagement. One type of authentic project that deserves attention from applied developmental scientists is youth participatory action research (YPAR), in which participants study a problem relevant to young people's lives and take action based on what they find. This combination of activism and inquiry can pose a cognitive challenge for participants, who must coordinate their emotional investment in a specific outcome with openness to unexpected or disconfirming evidence. We call this process managing bias. In this article we draw on qualitative data to show opportunities for youth to practice managing bias as part of an after-school YPAR project. In our conclusion we discuss implications of learning to manage bias for youth development processes and settings. (Contains 1 table and 2 figures.)