Transportation demand management (TDM) programs at employer worksites have been used with varying success across the United States since the 1970s. The overall purpose of these programs is for employers to encourage their employees to commute in modes other than a single-occupancy vehicle. Although employee commute options mandates have disappeared from many localities, the need to manage the demand for travel has not. Understanding what influences work trip mode choices can help transportation and planning agencies implement more effective TDM programs. Data from large worksites in the Portland, Oregon, region were used to evaluate how employer TDM programs, worksite characteristics, and location influence commute mode choice. Many factors contribute to the success of programs at different worksites. Success was measured in the percentage of commute trips made by transit and by walking and bicycling. Regression models showed that although subsidizing transit cost is effective, the choice of commute is also influenced by land use and transit access. Nonfinancial incentives, which can include flex time and a guaranteed ride home program, can also have a significant positive effect.