Based on Social Penetration theory, this study explores the topics that bloggers disclose on their blogs, and in the real world. A total of 1,027 Taiwanese bloggers participated in this online survey, which revealed that bloggers self-disclosed nine topics (attitude, body, money, work, feelings, personal, interests, experiences, and unclassified). Further, we examined the depth and width of what bloggers self-disclosed to three target audiences (online audience, best friend, and parents), confirming that their disclosure is significantly different for each of these target audiences. Bloggers seemingly express themselves to their best friends the most, followed by parents and online audiences, both in depth and in width. The ''wedge model,'' proposed by Altman and Taylor (1973), has been extended to online relationships in this study. In comparison to male bloggers, female bloggers seemed to disclose more to their best friends and parents in their daily lives; however, no significant difference was observed in their disclosure to online audiences. Younger bloggers ( < 20 years old) seemed to disclose a wider range of topics; however, there was no significant difference in the depth of their disclosure on their blogs. Discussions of these results are also presented.