Research has documented the influence of cultural values, beliefs, and traditional health practices on immigrants’ health care utilization in their host countries. We describe our findings of how Hmong immigrants to the United States make decisions about whether and when to use traditional and/or Western health services. We conducted semi-structured interviews with 11 Hmong adults. We found their decisions depended on whether they classified the illness as spiritual or not and how they evaluated the effectiveness of different treatment options for their illness. Hmong participants’ expectations for effective treatment in traditional or Western health care encounters combined with physical evidence of an illness influenced their decisions and often led them to shift from one type of care to the other. Understanding cultural differences in perceptions of the causes of illnesses and the link between perceived cause and treatment is important to improving care for the Hmong population.