Adoptive T cell therapy involves the ex vivo selection and expansion of effector cells for the treatment of patients with cancer. In this review, the advantages and limitations of using antigen-specific T cells are discussed in counterpoint to vaccine strategies. Although vaccination strategies represent more readily available reagents, adoptive T cell therapy provides highly selected T cells of defined phenotype, specificity and function that may influence their biological behavior in vivo. Adoptive T cell therapy offers not only translational opportunities but also a means to address fundamental issues in the evolving field of cancer immunotherapy.