Although integrating theories is often regarded as providing a more comprehensive understanding of a phenomenon, multi-theoretical studies are uncommon for three main reasons: deficient doctoral training, individual career considerations, and constraints of the journal review process. A multi-theoretical approach serves five functions. The first two − capturing the essence of complex strategic decisions and providing a more complete explanation of outcomes − are specifically related to the complexity of phenomena, while the remaining three − compensating for the explanatory deficiency of a single theory, exploiting the complementarity of theories and testing conflicting explanations − are mostly concerned with the limited scope and focus of a theory. The chapter offers some suggestions about promoting multi-theoretical studies, such as encouragement during doctoral training and by journal editors and reviewers, and collaboration with experts of different theories. Researchers should take precautions when adopting a multi-theoretical approach, such as reconciling inconsistent core assumptions of theories, addressing levels issues and beware of Ockham’s razor.