Enhancing the 21st Century Community Learning Centers Evaluation: A Concept Paper.

Describes how various components of Mathematica's complex study fit together and explains perspectives and principles related to 1) distinguishing implemented programs from intended ones, 2) ensuring broad coverage to explore competing theories of effective programming, 3) collecting longitudinal information on students and centers, and 4) measuring program impacts with control/comparison group designs. Also elaborates on the evaluation's conceptual framework.