This paper examines environmental and archaeological data for the Younger Dryas (YD) (12,900–11,600 calibrated years before present) (cal BP) and early Holocene (11,600–10,000\ cal BP) in the New England-Maritimes (NEM) to model environmental changes and possible human responses. For some other regions of North America, researchers argue for negligible environmental changes and human responses, while others suggest that ecological changes associated with cold conditions at the YD onset disrupted regional biota, causing subsistence stress for Paleoindian populations and the end of the Clovis cultural adaptation (circa 13,200–12,900\ cal BP). The NEM shows abrupt cooling at the YD onset, which fostered more open habitats favorable to both long-distance migrating and local herds of caribou, and may have encouraged early Paleoindian colonization and settlement of this unoccupied deglacial region. Comparison of the Paleoindian point sequence with calibrated radiocarbon dates indicates fluted point groups probably occupied the NEM during, but not after, the YD. Abrupt warming at the YD terminus (circa 11,600\ cal BP) caused a rapid reorganization of the region’s vegetation and prey species populations, coinciding in the archaeological record with a decline in Paleoindian biface fluting technology and altered regional site distributions. In the closed forests of the succeeding early Holocene NEM, late Paleoindian groups (11,600–10,000\ cal BP) used unfluted, lanceolate points that may signal post-YD immigration to the NEM.