Embodiments of the disclosure include methods and compositions for producing NKT cells effective for immunotherapy and also methods and compositions for providing an effective amount of NKT cells to an individual in need of immunotherapy. In specific embodiments, the NKT cells are CD62L+ and have been exposed to one or more costimulatory agents to maintain CD62L expression. The NKT cells may be modified to incorporate a chimeric antigen receptor, in some cases.