The evidence is overwhelming that a collaborative care approach to common mental illnesses is superior to usual care. Why isn't this model widely available? The authors of this column argue that the problem is not a lack of evidence or documentation of a better model, but the need for adoption of implementation science and dissemination knowledge to bring collaborative care into practice. They discuss the challenge of providing mental health care in the United States, the evidence that collaborative care is effective and can play a major role in expanding mental health services, the science of dissemination, six successful large-scale dissemination programs for collaborative care, and the implications of this shift in care delivery for psychiatry and all mental health providers.