Two experiments examined the interrelationship of subject-matter knowledge, interest, and recall in the field of human immunology/human biology and assessed cross-domain performance in the field of physics. Framed by a stage model of domain learning, cluster-analytic methods were used to group individuals on the basis of their performance on cognitive and affective measures in immunology. Resulting cluster profiles were compared with predictions expected from the stage model. Performance for students in these clusters was compared with their performance on similar measures in the field of physics. In Experiment 1, 30 premedical students and 17 graduate students in educational psychology served as participants. Results revealed 3 unique clusters of students that tended to conform to predictions of the domain learning model. Individuals' knowledge, interest, and recall of immunology generally paralleled their performance in the domain of physics. Experiment 2 sought to test and extend the findings of the initial experiment. Participants were 78 undergraduate students in education. Although 4 clusters emerged, patterns in knowledge, interest, and recall were similar to those revealed in Experiment 1.