Audit and feedback involves providing the receiver with a summary of their performance over a specified period of time. Audit and feedback interventions are commonly used to promote the implementation of evidence-based practices in health care due to their consistent effect size over time. While a commonly recognised intervention, the median absolute change when applying audit is 4.3%, with an interquartile range of 0.5–16%. This suggests that the mechanisms of audit and feedback need to be carefully considered to increase the likelihood of impact. This chapter contains a mix of evidence, theory and practical guidance for the development of audit and feedback. It is aimed at those who may be unfamiliar with this intervention, or unfamiliar with how the underpinning evidence or theory relates to audit and feedback design. Research to date suggests that interventions underpinned by theory may be more impactful, despite these theories being unwieldy for the uninitiated to use! This chapter is not a detailed analysis and application of the theory, but rather a way to explore and apply these concepts as an initial step.