How researchers identify and define levels of skill (e.g., what is an ‘expert’?) is surprisingly inconsistent across studies in expertise research. This lack of clarity regarding the definitions used in skill acquisition has obvious implications for scientists working in this area. More specifically, the accuracy and appropriateness of definitions for different levels of skill are central to the study of expert performance, from both a theoretical and methodological perspective. This presentation will summarize general approaches used in the past, highlight the need for clear delineations between groups of performers at different levels of skill and propose a taxonomy of sport-skill classification that could aid researchers in this area. This taxonomy is designed to provide a general system for categorizing skill across sport and delineates the various stages in skill acquisition. The taxonomy starts with early phases of skill development beginning with naïve (no skill) and novices (limited skill) and moves to transitional phases of development (basic, intermediate and advanced levels of skill) before reaching peak levels of skill (i.e., expert and eminence). Although there are limitations to any taxonomy of skill, continued attention and discussion of these issues are necessary to ensure that emerging evidence can be optimally integrated into the knowledge base regarding acquisition of sport skill.