This qualitative study examined how and why research experiences for teachers (RETs) influenced middle and high school science teachers' beliefs, attitudes, and values about teaching science as inquiry. Changes teachers reported after participating in the RET ranged from modifying a few lessons (belief change) to a comprehensive revision of what and how they taught to better reflect inquiry (attitude change). Some teachers who described comprehensively changing their instruction also described implementing actions meant to change science education within their respective schools, not just their own classrooms (value change). We present how and why teachers went about changes in their practices in relation to the researcher-created teacher inquiry beliefs system spectrum (TIBSS). The TIBSS conceptualizes the range of changes observed in participating teachers. We also describe the features of the RET and external factors, such as personal experiences and school contexts, that teachers cited as influential to these changes.