This article examines issues associated with assessing physical and perceptual cognitive components of agility. There are several associated challenges in designing effective training programmes that target these qualities in an effective and measurable manner. Given the methodological constraints associated with assessing the myriad components of agility, we will argue that when using assessments to guide training prescription aimed at improving agility, practitioners may need to deconstruct this quality into its constituent parts. Comparing physical assessment results with on-field performance enables the practitioner to make well-informed – albeit subjective – assessments of an athlete’s thinking speed.