The relative contributions of four individual difference variables to ability to solve analogically related problems in four separate problem sequences and for spontaneous and assisted transfer was examined. Subject were 116 university undergraduates enrolled in an introductory psychology course who volunteered to participate for course credit and 65 high school seniors who volunteered to participate for extra credit from their social studies teacher. Specifically examined was whether combinations of individual difference variables served as significant predictors of problem-solving success in four different source-target problem sequences. For spontaneous transfer, the results indicate that under certain circumstances different combinations of individual difference variables contribute to the ability to predict whether a subject would provide a particular solution to a target problem. For assisted transfer, individual differences do not account for the ability to predict whether a subject would provide a particular solution to a target problem. Results are discussed in terms of why the individual difference variables enhance prediction for spontaneous transfer only under certain circumstances. In addition, suggestions for pursuing this line of inquiry are provided. Four tables present study data. Appendix A contains a logic problem from the study, and Appendix B contains the source and target analogues. (SLD)