This volume teams up familiar literature in knowledge utilization with related theories of diffusion, implementation, transfer, and translation. Each of these knowledge-for-action theories is reviewed for its disciplinary roots, assumptions about change, key variables, and contextual influences. Cross-talk among these heretofore parallel theories identifies priorities and implications for evaluation practice. This issue provides evaluators with multiple lenses to capture change, including a consideration of complexity, rather than succumb to single-discipline perceptions of value. If we think about the new knowledge enshrined within a policy or program under evaluation as the foreground, then complexity invites evaluators to think more critically about the background, that is, the dynamic properties of the setting or system into which a policy program is introduced and the implications this raises for evaluation. This is the 124th volume of the Jossey-Bass quarterly report series New Directions for Evaluation, an official publication of the American Evaluation Association.