Many people propose closing crop yield gaps as a means to address food security concerns. But concepts of yield gaps vary and the linkages to food security are complex. Yields are an object of choice for farmers, so a meaningful interpretation of yield gaps requires giving weight to both the economic and biological realities of crop production. We clarify the terminology surrounding yield gaps, show that closing yield gaps is not necessarily economic, and conclude that food security will be better served by policies that directly enhance the productive capacity of agriculture to supply affordable food efficiently and sustainably.