Culverts are sometimes mentioned along with bridges in the context of transportation infrastructure that provides bat roosting habitat; however, there is limited literature specific to bat roosts in culverts despite the fact that these structures often have high conservation value to bats in certain landscapes and regions. Data collected throughout Southern California over a 14-year period show that many bat species roost in a variety of culvert structures associated with road and railway transportation alignments; these include concrete box culverts, concrete arch culverts, concrete pipe culverts, and corrugated metal pipe culverts. Occupied culverts are found in a variety of habitats, including heavily urbanized landscapes, and bats have been documented day roosting (including maternity roosting), night roosting, and even mating within culvert structures. Day roost features often used by bats in culverts vary widely and can include overlap joints, expansion joints, manhole access shafts, drainage pipes, open concrete surfaces, and bird nests. Misconceptions about what constitutes suitable roosting habitat for bats in culverts can result in these structures being overlooked during the environmental review process, and consequently impacts to bats roosting in culverts are often not adequately minimized or mitigated. Because roosting habitat is a limited and declining resource for bats, overlooking culverts or less-commonly encountered features in culverts as roosts can have profound conservation and management implications. Case studies and successful strategies for minimizing and mitigating impacts to bats in culverts will also be discussed.