OBJECTIVES: Interprofessional collaboration and team-based care have been regarded as important approaches to improve health care. Factors enhancing and prohibiting interprofessional collaboration in practice settings, however, are not fully understood. This study provides an updated literature review on factors influencing interprofessional collaboration from 2004-2011. METHODS: Databases including ABI/INFORM Global, CINAHL Plus, MEDLINE, PsycINFO, Sociological Abstracts, and ProQuest Dissertations & Theses were searched using keywords such as collaboration, team, interprofessional, interdisciplinary, determinant, and factor; and subject headings such as interprofessional relations (MeSH) and multidisciplinary care team (CINAHL). Only empirical studies conducted in patient care settings examining interprofessional collaboration were retained. Due to the large number of hits, article titles were screened prior to abstract screening and retrieval of full articles. Salient systematic, organizational, and interactional factors identified from the articles were summarized respectively. RESULTS: Over 7000 article titles were screened, 680 abstracts were retrieved, and 110 articles were retained. A wide range of qualitative (N=66), quantitative (N=34), and mixed methods (N=10) were used in these studies. The main systematic factors included regulatory and economic incentives, as well as professional culture differences and dominance of medical power. Organizational factors included leadership, physical space, staffing, and team training. Interactional factors, which have been studied the most extensively, included communication, team climate, shared purpose, awareness and respect.  Additional factors included complexity of patient cases and team artifacts. Since a previous literature review by San Martin-Rodriguez et al. in 2005, many more studies have examined organizational determinants, yet studies regarding systematic factors, such as health care systems, remain scarce. CONCLUSIONS: Interprofessional collaboration is influenced by systematic, organizational, and interactional factors. Policies targeting multi-level aspects may be helpful in enhancing interprofessional collaboration and ultimately improving patient care. Future studies are needed to examine factors beyond the interactional level and their relationships with patient outcomes.