Objectives: This dissertation includes two studies. Study one aims to uncover sexual identity development and examine the differences in psychosocial health outcomes across various age, gender, and regional groups. Additionally, study two explores distinctive internalized stigma profiles that impact bisexual people’s psychosocial health outcomes and inspect the moderating effect of the latent classes of internalized stigma on the relationship between demographic characteristics of Chinese bisexuals (e.g., region, gender, age) and their health outcomes.Methods: An internet-based survey was administered to 685 respondents, from June to August 2021, reached primarily via lesbian, gay, bisexual, and transgender community organizations and professional networks. Participants reported their a battery of measures such as demographics, identity milestones, internalized stigma, and psychiatric symptoms. Results: Study one found that significant gender, and regional differences were observed regarding bisexual identity milestones. Individuals who were older, transgender and nonbinary identifying, and based in Taiwan disclosed their sexual identity more. Alarmingly, all respondents reported clinically elevated depression and anxiety symptoms, with a majority experiencing moderately severe depression (60%) and moderate or severe anxiety (80%). Approximately half of respondents contemplated suicide in the past year. Transgender and nonbinary bisexual individuals faced a higher risk of psychiatric symptoms and reduced subjective well-being compared to cisgender respondents, but having enhanced self-esteem served as a significant protective factor. In study two, latent profile analysis identified three bisexual subgroups: Self-appreciating (85.83%), Self-doubting (7.56%), and Self-dissonant (6.61%). Cisgender men, transgender and non-binary persons were significantly more likely than cisgender women to be in Self-doubting relative to Self-appreciating. Religious respondents were significantly more likely to be in Self-doubting relative to Self-appreciating. Respondents based in Taiwan were less likely to be in Self-doubting relative to Self-appreciating, compared to those based in mainland China. Self-appreciating individuals reported the lowest levels of depression, and the greatest levels of subjective well-being, and outness. The Self-doubting group reported significantly higher levels of outness than Self-dissonant. There were no significant group differences for LGBTQ community connectedness. Additionally, greater levels of IB, but not IH, was correlated with reduced well-being and more anxiety, depression, and suicidal ideation (r = -.22 to .08). Finally, internalized stigma latent classes influenced the relation between depression and region. Residing in Hong Kong was beneficial to Self-doubting and Self-dissonant participants since their depression levels did not increase compared to the Self-appreciating group, as those who lived in mainland China did. There were no significant moderating effects of community connectedness. Implications for future research, clinical interventions, and public health policies were discussed.