Investigates commonly cited experiential qualities (internal locus, volition, perceived choice) to propose a model of the essential nature of perceived self-determination in intrinsic motivation. Results supported model in which internal locus and volition, but not perceived choice, constitute valid indicators of self-determination. Discusses conundrum of choice by proposing conditions under which teachers can expect choice to increase students' intrinsic motivation. (Contains 96 references, 8 tables, and 4 figures.) (GCP)