The purpose of this article is to review research related to the practitioner’s contribution to effective service delivery. Specifically, we answer five questions. First, what are sport and exercise psychology practitioners striving to achieve? Second, what is expertise in applied sport and exercise psychology? Third, what are the characteristics of effective practitioners? Fourth, how can practitioners develop their expertise over time? Fifth, how do practitioners manage the athlete variables and contextual factors that influence service delivery? Offering answers to these questions allows us to identify practical implications to inform practitioner training and development and to suggest avenues to expand knowledge. Results from the review suggest that practitioners who help athletes effectively possess facilitative interpersonal skills, experience professional self-doubt, engage in judicious decision making, exercise organisational savviness, demonstrate multicultural humility, and willingly engage in skill development. Based on current knowledge, future research directions include examining the magnitude of practitioner attributes on service delivery outcomes. Applied implications for professional development include the use of deliberate practice to enhance skill learning, along with using supervision and feedback.