Genentech

Approximately 340 of the biotech company’s employees spend an hour each week mentoring students from South San Francisco elementary schools. Adrienne Melton, senior planning and execution manager, has participated in the program since joining Genentech in 2011; she spent three of those years mentoring the same student. Serving for a sustained stretch of time, says Melton, has enabled her to see “the lasting impact of my volunteer work.” Read the Great Place to Work review here.