Bunnell et al. (2009) introduced the concept of Stewardship Responsibility (SR) rankings as a tool for conservation planning, using global rankings of rare species in British Columbia. I applied a version of their tool to assess biodiversity distributions in New York State Parks, using records collected by the N.Y. Natural Heritage Program. Comprehensive surveys were conducted among 150 parks over a decade, leading to a database of 1074 records for 312 rare species and 98 significant ecological communities. I applied SR ranks in a nested design — agency-wide — among regions within the agency and across the state (comparisons with other management entities). Subsets of parks and regions ranked more highly than others, but most parks contain at least one rare species and significant ecological community, indicating a broad distribution of important biological resources. Statewide, the agency maintains a very high SR rank profile in proportion to its land area (< 1% of the state), with 43% of all New York rare species found in at least one State Park, and 30 species fully or primarily dependent on the agency for their protection. Taking this information a step further, I developed a set of park-by-park Natural Heritage Biodiversity Profiles, which emphasize unique contributions of each park in ways designed to inform the general public. Although many state and provincial park systems emphasize their recreational features, probably all make critical contributions to biodiversity conservation, and tools like these can be used to illustrate and enhance those contributions.