AbstractEnvironments of disk‐dominated galaxies and simple disk systems‐compared to systems with bulges‐provide a means to explore how environment relates to galaxy morphology. Our approach focuses on systems with edge‐on disks where disk‐to‐bulge ratios and disk flattening can be unambiguously determined and focuses on simple disks as evolutionary tracers. We study possible physical neighbors around the target disk galaxies and seek statistical relationships between local galaxy density and galaxy morphology. Galaxies consisting of simple stellar disks exist in environments ranging from the relatively the isolated field to moderate density galaxy groups. This distribution overlaps with that of systems with prominent bulges, although galaxies with large bulges are systematically rarer at low densities. The presence of simple disk galaxies in isolation and also in moderate density galaxy groups suggests that simple disks develop naturally in low density regions but have a limited ability to survive significant interactions with other galaxies. Simple disks thus are rare in denser galaxy systems where galaxy transformations are frequently driven by intense initial merging and later strong interactions (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)