Electric transportation has many attractive features in today's energy environment including decreasing greenhouse gas emissions from the transportation sector, reducing dependence on imported petroleum, and potentially providing consumers a lower cost alternative to gasoline. Plug-in hybrid Electric (PHEV) vehicles represent the most promising approach to electrification of a significant portion of the transportation sector. Electric power utilities recognize this possibility and must analyze the associated impacts to electric system operations. This paper provides details of analytical framework developed to evaluate the impact of PHEV loading on distribution system operations as part of a large, multi-utility collaborative study. This paper also summarizes partial results of the impact of PHEVs on one utility distribution feeder.