Manuscript Type Review Research Question/Issue This study reviews previous country‐level and firm‐level studies on corporate governance codes up to 2014 in order to highlight recent trends and indicate future avenues of research. Research Findings/Results Our data show that research on codes increases over time consistently with the diffusion and the relevance of the empirical phenomenon. Despite previous studies substantially enriching our knowledge of the antecedents and consequences of governance codes, our study shows there are still several opportunities to make significant contributions in this area. Theoretical Implications Agency theory is the dominant theoretical framework, although other theoretical perspectives (especially the institutional one) are increasingly adopted. Future studies should be aimed at widening and combining various theoretical lenses so as to develop new interpretations and a better understanding of governance codes. Practical Implications Legislators and policymakers should continue to develop and update the recommendations of national governance codes in order to address the potential failures of corporate governance mechanisms in place.