This study examines the extent of development and current state of co-innovation studies, which have been published over the last 25 years. Systematic search in three extensive databases resulted in 216 co-innovation related articles. A content analysis of these articles was performed using multiple classifier variables. The findings display several characterizations of co-innovation research, including general publication characteristics, most studied research topics, theoretical approaches and perspectives that have been applied, research designs, and research contexts.  Based on the findings, paths for future research are laid.