In the face of severe financial challenges and demands to improve quality and service to patients, many community health centers (CHCs) have aligned or integrated with other CHCs, physician groups, or hospitals. Yet the nature of and rationale for these organizational decisions are not well understood. Our research applied an organizational theoretical framework to test whether strategic adaptation theory or institutional theory best describes the integration activity of CHCs in Ohio. We collected primary data from case studies of seven CHCs selected for geographic representation and studied December 2000-January 2001. Semi-structured interviews and a case study database supported our chain of evidence. We found that CHC integration activity was substantial (five of seven CHCs integrated) and extremely varied. Consistent with strategic adaptation theory, we determined that CHC integration actions were predominantly center-specific, rational responses to environmental challenges and were initiated to improve operations or financial performance. Rarely did CHCs initiate major organizational change merely to mimic other CHC actions, as might have been expected of highly institutionalized organizations. Understanding the basis for CHCs' strategic decisions while monitoring financial health will remain critical as lawmakers and administrators work to develop policies that both maintain progress made and improve primary care access for the poor, the uninsured, and those with special health care needs served by these important safety net providers.