Community coalitions (CCs) have labored with some difficulty to demonstrate empirical evidence of effectiveness in preventing a wide range of adolescent problem behaviors. Training and technical assistance (TA) have been identified as important elements in promoting improved functioning of CCs. A reliable, valid, and inexpensive method to assess functioning of CCs has been developed and is tested in this article in the context of Pennsylvania's Communities That Care (CTC) model. A CC Web-based questionnaire was developed and administered to more than 79 communities (867 participants) and the validity and reliability were assessed through multiple means, including the use of a companion TA implementation feedback questionnaire completed by TAs assigned to each of the sites. Results indicated adequate to good psychometric properties on internal reliability of the Web-based questionnaire, moderate construct validity across different reports of functioning, and relative stability throughout the course of 1 year. Implications for a variety of community prevention coalitions interested in a relatively low-cost, user friendly, and suitable methodology for evaluating coalition functioning are discussed. In addition, areas of application for future research including linking coalition functioning with the quality and nature of technical assistance, levels of risk and protective factors, and large data sets of youth risk factor and problem behavior data are highlighted. (Contains 3 tables.)