This document provides guidance for ancillary material (AM) suppliers to maintain a high level of lot-to-lot consistency in the aspects of identity, purity, stability, biosafety, performance, as well as the accompanying documentation. This document is applicable to cellular therapeutic products, including gene therapy products whereby cells form part of the final product. It does not apply to products without cells. The AMs described in this document include those of biological origin [e.g. sera, media (including media additives), growth factors, and monoclonal antibodies] and chemical origin. This document does not address dimethyl sulfoxide (DMSO) for cryopreservation, beads, scaffolds, feeder cells, apparatus and instruments, or additives used post bioprocessing. This document does not cover the selection, assessment or control of starting materials and excipients. NOTE International, regional or national regulations or requirements can also apply to specific topics covered in this document.