My Class Activities (MCA) is an instrument that has been used for evaluation of university-based Saturday enrichment programs, but was originally normed using students in regular schools. A sample of MCA scores from 826 students in grades 3-8 from a Saturday enrichment program was used. Four different MCA models were evaluated: (a) the original MCA model containing interest, challenge, choice, and enjoyment; (b) a model including a second-order term connecting enjoyment and interest; (c) a three-factor model containing a combination of interest and enjoyment, challenge, and choice; and (d) the original MCA model after two items were removed. Results indicated that the original MCA four-factor structure provided a better ft when used with the Saturday enrichment sample than did the second-order and the three first-order factor models. However, the best solution regarding model fit was found using the original model, but with the removal of two poorly functioning items. This study highlighted the importance of evaluating an instrument whenever used with a different population than that on which it was originally normed. With two items deleted from the challenge scale, MCA is a potential tool for use in enrichment program evaluation that provides measures of four motivational dimensions often emphasized in programs for high-ability students. (Contains 4 tables.)