Youth activity involvement has received increasing research and theoretical attention and should be of particular interest to social development investigators. Involvement has been correlated with a wide range of positive developmental indices, although not for all activities nor for all children. However, our ability to interpret such findings has been restricted by measurement and design limitations. Greater attention needs to be given to assessment issues and to determining the unique effects of psychological vs. behavioral engagement, as well as to capturing the dynamic nature of engagement and the moderating role of individual differences. "Big picture" models of the entire engagement process (such as the one presented here) will help identify gaps in our research knowledge and will integrate existing evidence and theory.