Smooth muscle cells (SMCs) play a key role in vascular physiology and pathology. An appreciation of normal SMCs developmental mechanisms will likely lead to a better understanding of disease processes and potentially to novel treatment strategies. We present a method for generating relatively pure populations of SMCs from embryonic stem cells (ESC) which display appropriate excitation and contractile responses to vasoactive agonists. We also present protocols for assessment of SMCs purity and identity by immunofluorescence, quantitative RT-PCR, and FACS. This ESC-based system has tremendous potential for studying developmental regulation of SMC lineage, as well as for possible SMC tissue engineering.