James Needham and Cornelius Betten in 1901 published one the first studies of aquatic insects in North America providing life history information for a number of taxa, and descriptions of 10 new species and two new genera from the Adirondacks in New York. However, since this early publication, relatively little taxonomic research and field surveys have been conducted targeting aquatic insects in the Adirondack Park. The diverse array of aquatic habitats present in New York harbors numerous aquatic insect taxa. Research funded by the NYSDEC State Wildlife Grants and the NYS Biodiversity Research Institute on Ephemeroptera, Plecoptera and Trichoptera biodiversity in eastern New York have resulted in the first ever comprehensive assessment of aquatic insects in the region. Distributional records were obtained from primary literature, institutional collections and field surveys. During our four-year study of the Park more than 25,000 specimens from 465 locations were examined. We report 509 species of EPT from the Adirondack Park of which 99 are reported from New York State for the first time. Our field surveys have also resulted in the discovery of several species new to science and numerous species of conservation concern.