Psychological factors that may underlie the consistent gender and ethnic group differences found in science achievement were studied in a sample of 557 college students (297 male and 260 female) taking the first semester of a 2-semester sequence in organic chemistry. About 70 percent were Caucasian, with 23 percent Asian and 37 percent African American and Hispanic American. When comparing the correlates of course performance by social group, the strongest correlates were found to be: (1) prior achievement and motivation for African American and Hispanic American students; (2) prior achievement and learning strategies for Asian and Caucasian students; (3) prior achievement and motivation for males; and (4) prior achievement and learning strategies for females. However, in a multivariate analysis, gender and ethnic differences in performance were washed out once prior achievement, motivation, and use of learning strategies were recognized. Availability of science programs in secondary schools, curricula that promote student motivation, and direct learning strategy instruction may be ways to address gender and ethnic gaps in science achievement. (SLD)