Undergraduate student interest in aging was examined in relation to age, gender, and contact with older adults. Interest in aging is conceived of along a continuum, ranging from initial interest-taking an aging course-to substantial interest as evidenced by academic and career interest. Undergraduate students who have taken an aging course (n = 189) and a stratified random comparison group (n = 261) self-assessed their interest in aging. Background information, including the frequency and duration of contact with older family and non-family individuals, was reported. Being female (p < 001) and having frequent contact with older family members (p < .01) significantly explains initial interest in aging. Initial interest in aging (i.e., taking an aging course) significantly contributes to substantial interest in aging (p < .0001) i.e., taking more aging courses, majoring in gerontology, working or planning to work with older adults. Contact with older adults positively affects undergraduate interest in aging. Interest in aging proceeds along a continuum, from preceding factors to initial interest in aging and then to substantial interest in aging. Aging courses and opportunities for interaction with older adults should be offered at the undergraduate level. [ABSTRACT FROM AUTHOR]