Abstract: The invention relates to novel artificial antigen presenting cells (aAPCs). The aAPC comprises at least one stimulatory ligand and at least one co-stimulatory ligand where the ligands each specifically bind with a cognate molecule on a T cell of interest, thereby mediating expansion of the T cell. The aAPC of the invention can further comprise additional molecules useful for expanding a T cell of interest. The aAPC of the invention can be used as an “off the shelf” APC that can be readily designed to expand a T cell of interest. Also, the aAPC of the invention can be used identify the stimulatory, co-stimulatory, and any other factors that mediate growth and expansion of a T cell of interest. Thus, the present invention provides powerful tools for development of novel therapeutics where activation and expansion of a T cell can provide a benefit.