Cover crops (CCs) provide ecological benefits but concerns about reduced cash crop yields limit their adoption. This study evaluated CCs and tillage systems combinations at three locations across Ontario. The goal was to identify combinations leading to large CC biomass accumulation while improving or maintaining corn yields. Generally, CC bi-cultures or polycultures produce more biomass in both fall and spring than CC monocultures. Corn yield generally increased over non-CC controls when following a CC that included a legume as a monoculture, bi-culture or polyculture. Generally, other CC treatments had no significant effect on corn yield. Corn yield was not impacted by tillage practices at any site-years. The lack of significant CC or tillage effects on corn yield may have been caused by starter fertilizer, row cleaners with planters and sub-optimal nitrogen fertilizer used in this study. Further information would help to achieve regionally specific CC recommendations to increase corn production.