Advanced Therapy Medicinal Products (ATMPs) are based on genes, cells, or tissues delivered to patients to provide a therapeutic benefit based on a specific target of interest. For ATMPs, the therapy is cells, engineered tissues, or the manipulation of the patient’s genome. This is in contrast with traditional manufacturing processes for compounds that are synthetically derived (i.e., small molecule) or proteins or peptides expressed by cellular systems (i.e., large molecule biopharmaceuticals). The development, regulatory path, facility design, qualification, and manufacture of ATMPs present significant challenges to manufacturers, engineers, and suppliers. The GMP regulations are evolving as novel processes are presented and manufacturing paradigms are being tested. This Guide addresses facility engineering issues that are most applicable at the time of publication, as based on the experience of the authors. This Guide focuses primarily on allogeneic cell therapies, specifically manufacturing facility development and design. Allogeneic cell therapies have unique challenges due to the small manufacturing scale, limitations in scale-up, the need to manufacture multiple lots of products concurrently, and the need for flexibility to accommodate a varied and evolving product portfolio. This Guide covers common challenges with allogeneic cell therapy facilities, design concepts specific to allogeneic cell therapy facilities, and GMP layout and architectural design development. Key aspects of the allogeneic cell therapy manufacturing process, including sampling, QC, and process understanding, are presented. Not included in the scope of this Guide are the following areas: Manufacture of allogeneic cell therapies for non-parenteral use Tissue-based allogeneic products Processing or manufacture of ATMPs in a clinic/hospital setting Manufacture of medical devices or components used in combination devices that involve ATMPs While this Guide focuses on allogeneic cell therapies to the greatest extent possible, the authors recognize a significant amount of content is applicable to other types of ATMPs, particularly around regulatory compliance, technology transfer, utilities, HVAC, and supply chain. The framework of this Guide has been built upon the ISPE Guide: Advanced Therapy Medicinal Products – Autologous Cell Therapy in order to create cohesive content between thetwo modalities that have significant overlaps.