This study investigated preservice and inservice teachers' perceptions of appropriateness of teacher self-disclosure. A sample of 180 preservice teachers and 135 preK-12 teachers participated in the study. Results showed statistically significant differences between the groups of teachers in their perceptions of appropriateness of teacher self-disclosure in the three dimensions: Uncommon Topics, Uncommon Purposes, and Consideration of Students. No significant differences were found in the two dimensions: Common Topics and Common Purposes. This study makes an excellent contribution to the theoretical framework of the study of teacher self-disclosure and also provides implications for teaching and teacher education. (Contains 4 tables.)