**Talk Abstract** Heart rate variability (HRV) is the complex modification of the heart rate over time. HRV is a popular tool to non-invasively index autonomic control of the heart, as lower HRV is an accurate index of reduced parasympathetic activity. More recently, there has been a particular interest in linking HRV with both state and trait behaviours. For instance, several psychiatric illnesses have been associated with reduced HRV, suggesting that cardiac autonomic dysfunction contributes to the pathophysiology of these disorders. Moreover, various cognitive processes (e.g., theory of mind, cognitive flexibility) have also been shown to be related to HRV. While HRV data is relatively easy to collect, there are a number of crucial considerations when making inferences from HRV data. The purpose of this workshop is to provide a brief primer on HRV, provide guidance on what to consider when planning a HRV study, outline various methods for the collection of HRV data, and to describe how to calculate HRV data.