In this paper we examine specific issues relating to the assessment of imagery ability and highlight how they are related to the development and evaluation of a multidimensional, multi-modal measure of sport imagery ability. We describe the development of the Sport Imagery Ability Measure(SIAM),which is a 72-item self-report questionnaire that uses six sport related scenes to examine the dimensions of vividness, control, duration, ease, and sped of generation: the visual, auditory, olfactory, gustatory, tactile, and kinesthetic senses; and the experience of emotion. To examine reliability and factor structure, participants from high schools (n = 279), university physical education courses (n = 1 76), and a junior elite sports group (n = 19) completed the measure at their respective organizational settings. The internal consistency scores (Cronbach's alpha) for each of the 12 subscales indicated adequate reliability with values rangingfrom .63 (ease) to .8 (olfactory). Results of an exploratory factor analysis on the subsale scores suggested a two-factor structure for the subscales. To test the temporal stability of the SIAM, 47 university students completed the measure a second time after a 4-week interval. Results revealed moderate but significant subscale test-retest correlations, varying from .44 (speed) to .83 (gustatory). We consider several critical issues related to the construction and validation of measures of imagery. We also discuss implications for further psyhmetric analysis and application of the SIAM.