When multiple treatment choices are available, the question is not just "which treatment is the best?" but more importantly "best or better for whom, when, and why?" Aptitude (or attribute) by treatment interaction (ATI) is a research paradigm that attempts to examine exactly that--how outcome depends on the match or mismatch between patients' specific characteristics and the treatments they receive. The purpose of this two-part paper is to introduce ATI methods as a conceptual framework into complementary and Alternative medicine/integrative medicine (CAM/IM) outcome research. Part I presented key concepts in ATI research. Part II presents ATI research designs and discusses their applications to the examination of the relationships between individuals and therapies, and the illumination of the mechanisms that make therapies differentially effective. Based on this examination, we conclude that ATI research offers invaluable insights into the multifaceted package of care typically delivered in contemporary medicine and therefore should be included in the portfolio of all CAM/IM outcome research.