The commute trip reduction (CTR) program is an employer-based regional transportation demand management (TDM) effort initiated in Washington State in 1991. Through the CTR law, major employers in the nine largest counties are required to develop and implement TDM programs for their employees. As a result of the law, nearly 900 employers have developed programs affecting over 460,000 employees. The CTR statute requires an evaluation and periodic reports to the state legislature. The first formal report on the program's design and implementation was presented to the legislature in December 1995, thus ending the first phase of the program. To date, employers have fully developed and implemented their work-site programs, surveyed for their base year single-occupant vehicle and vehicle miles traveled rates, and completed their first measurement survey, and are assessing their ability to achieve the 1997 and 1999 CTR goals. As employers begin Phase 2 of the CTR program, they are raising concerns about some of the barriers they face in implementing the program. The effect of the CTR program on employers is considered, some of the lessons learned during Phase 1 are outlined, and how to translate these lessons into program improvements for CTR or other employer-based TDM programs is discussed.