This study examined whether students who left biomedical fields of study during college did so primarily because they became disenchanted with those fields or because they felt attracted to alternative fields of study. We identified 1,193 students intending to pursue biomedical fields of study early in college, collected data about their beliefs and performance throughout college, and interviewed them near graduation about their future plans. Descriptively, we examined the topics students discussed as affecting their attrition decisions. Predictive research aims were to determine how academic performance, interest, and demographic factors predicted students' likelihood of overall attrition and likelihood of reporting distinct reasons for attrition. Among the 192 students who left biomedical fields, 62.5% described leaving only in terms of feeling disenchanted, whereas 37.4% expressed that they left at least in part due to feeling attracted toward nonbiomedical fields. Most students who left biomedical fields expressed changing plans for reasons related to interest; this was especially prevalent among students who reported leaving due to attraction toward nonbiomedical fields. Predictive analyses showed that interest in biology and grades at the end of an introductory biology course predicted the likelihood of overall attrition and likelihood of leaving due to feeling disenchantment, whereas underrepresented ethnic minority status predicted these outcomes positively. Interest and course grades also predicted the likelihood of students leaving due to feeling attraction toward other fields, but interest was a stronger predictor relative to grades. Results highlight distinct types of attrition that may have implications for policies to promote STEM retention.