We report on an eastern coyote or coywolf (Canis latrans × lycaon) pack in a heavily urbanized area at the northern edge of Boston, Massachusetts, living at a high pack density. We radio-collared four members of this social unit, a breeding pair and two of their juvenile offspring and tracked them from May 2004–Apr. 2005. The pack had a small cumulative territory area (overall = 2.05 km2), yet lived at a normal group size (fall = 6–7, winter = 4) for coyotes/coywolves in eastern North America. Fall density for this pack was 2.92–3.41/km2 and winter density was 1.95/km2, representing the highest recorded density for coyotes in this region.