Using 2003 US data, this paper examines job satisfaction and economic returns to science and engineering (STEM) baccalaureate recipients who obtain STEM PhDs or professional degrees in the fields of law, MBA, medicine, and MS engineering. The salient finding of this research is that the future STEM PhD supply will largely be determined by the availability of tenured academic positions. Despite inferior economic returns, job satisfaction for STEM PhD recipients significantly exceeds that of other professional degree recipients except for medicine. Superior job satisfaction for STEM PhDs results almost entirely from employment in tenured academic positions. 55 percent of STEM PhDs working outside the academic sector have similar job satisfaction compared to professional degree recipients but without the economic rewards. This analysis further suggests STEM PhDs would not have higher job satisfaction if they had completed degrees in medicine or law instead of PhDs. The policy to increase STEM PhD employment in the US economy has focused on supply. The findings of this paper indicate that a demand-side focus may be a more effective policy and that the future STEM PhD supply will be largely driven by the availability of full-time tenure-track academic job openings.