To provide an overview of the science and practice of knowledge translation. Narrative review outlining what knowledge translation is and a framework for its use. Knowledge translation is defined as the use of knowledge in practice and decision making by the public, patients, health care professionals, managers, and policy makers. Failures to use research evidence to inform decision making are apparent across all these key decision maker groups. There are several proposed theories and frameworks for achieving knowledge translation. A conceptual framework developed by Graham et al., termed the knowledge-to-action cycle, provides an approach that builds on the commonalities found in an assessment of planned action theories. Review of the evidence base for the science and practice of knowledge translation has identified several gaps including the need to develop valid strategies for assessing the determinants of knowledge use and for evaluating sustainability of knowledge translation interventions. Copyright © 2011 Elsevier Inc. All rights reserved.