Despite increased focus on the effects of organized activities on youth development, there is currently no consensus about the best way to assess various dimensions of involvement. This article explores the complexities of assessing involvement and focuses specifically on the following organized activity dimensions: (a) breadth, (b) intensity, (c) duration/consistency, and (d) engagement. For each dimension, the article examines the theoretical underpinnings for why it is important to measure the dimension, presents measurement issues that have arisen in previous studies, describes how the dimension relates to developmental outcomes, and offers recommendations for assessing it in future use. A conceptual model is presented to describe issues that are important to consider when assessing various dimensions of organized activity involvement in future research. (Contains 1 table and 1 figure.)