A search of large, H I–rich disk galaxies finds a significantly higher fraction of low-luminosity active galactic nucleus (AGN) signatures compared with other late-type galaxies. Approximately half the galaxies selected in this sample have AGN-like behavior in their cores; the rest have H II nuclei resulting from simple star formation. Since AGN behavior is not evident in all the sample galaxies, which where selected by high gas mass, we speculate that it is the fuel flow rate that is the common feature between late-type low surface brightness disks and other active nuclear galaxies.