Human failure events (HFEs) are the unit of analysis in human reliability analysis (HRA). HFEs are essentially human errors that have an adverse consequence on system safety. In HRAs in the nuclear power industry, HFEs are typically defined in the probabilistic safety assessment (PSA), staring with possible hardware failures and then identifying opportunities for human action or inaction to affect those failures. In other industries, the HFE may not be predefined in this manner. For example, in the case of some oil and gas applications, the overarching quantitative risk analysis (QRA) does not identify HFEs. As human factors experts perform HRAs, there is difficulty in characterizing human actions in such a way that they represent the right level of analysis suitable for inclusion in the PSA or QRA. This paper provides guidance to help analysts in such a situation. The paper presents seven steps to build suitable HFEs based on an initial human factors task analysis.