Agricultural researchers and science librarians must understand which research literature databases provide the most comprehensive coverage of agricultural subjects to support research inquiries. Once the domain of a few specialized databases, agricultural research literature is now covered by broad, multidisciplinary databases. The purpose of this study was to determine the most comprehensive database(s) for agricultural literature searching in terms of the scope of agricultural subject content provided by each database. We compared eight databases that cover a sample set of agricultural research literature for a range of agricultural sub-topics to determine how much overlap exists and which database(s) best support discovery of agricultural research literature. We found that the multidisciplinary databases provided the most comprehensive coverage and that one of the agriculture specific databases matched the coverage provided by the multidisciplinary databases. This study will help researchers and librarians determine where to invest their effort and resources when looking to find agricultural research content.