Self-reported reasons for concealing suicidal ideation were explored using data from a national survey of undergraduate and graduate students: 558 students indicated that they seriously considered attempting suicide during the previous year and did not tell anyone about their suicidal thoughts. Content analysis of students' qualitative responses to the question "Why did you choose not to tell anyone about these thoughts?" generated nine reasons: (a) perceived low risk, (b) concern for others, (c) dispositional privacy, (d) pointlessness of help-seeking, (e) others' negative reactions, (f) personal negative reactions, (g) repercussions, (h) interference, and (i) perceived isolation. Implications for campus suicide prevention are discussed. (Contains 2 tables.)