The New River Mesa Quadrangle is located along the northern fringe of the Phoenix metropolitan area. The quadrangle includes several high-standing mesas, and although the rugged terrain of the New River Mesa area is undeveloped, the area to the south is becoming increasingly urbanized and is undergoing rapid population growth. Geologic mapping was related to other previous and ongoing mapping projects of urban fringe areas located to the north and northeast of the Phoenix metropolitan area. A series of color 1 : 24,000-scale aerial photographs (dated 11-5-79 and 6-11-88) were obtained from the U. S. Department of Interior and the Tonto National Forest office in Phoenix, and these were used by the field geologists to assist with mapping and to identify contacts in areas where access was limited due to private land holdings. This study is contiguous with geologic mapping recently completed in the Humboldt Mountain Quadrangle to the east (Gilbert and others, 1998). Road access for most parts of the quadrangle is limited. Portions in the southwestern corner along lower Cave Creek are accessible on Forest Road 48 from Cave Creek. Grapevine Wash, in the southeast corner, is accessible along private roads that serve subdivisions north of Carefree. The northern third of the map area is accessible from a system of primitive Forest Roads that can be reached from graded Forest Roads 24, 41, and 17 from the north and east of the map area. Additional roads that provide access to inactive mines or mining claims are commonly locked and not accessible to the public. Most of the land and trails within the map area are administered by the Tonto National Forest, and areas in the east-central part of the map area were reached by walking or horseback along a welldeveloped trail system. Report and geologic map of the New River Mesa 7.5' Quadrangle, Maricopa County, Arizona, scale 1:24,000.