We describe ethical issues that emerged during a one-year CBPR study of HIV and human papillomavirus (HPV) vulnerabilities and prevention in two Pacific Islander (PI) communities, and the collaborative solutions to these challenges reached by academic and community partners. In our project case study analysis, we found that ethical tensions were linked mainly to issues of mutual trust and credibility in PI communities; cultural taboos associated with the nexus of religiosity and traditional PI culture; fears of privacy breaches in small, interconnected PI communities; and competing priorities of scientific rigor versus direct community services. Mutual capacity building and linking CBPR practice to PI social protocols are required for effective solutions and progress toward social justice outcomes.