This guide outlines best practices for managing non-case report form (non-CRF) data within the clinical development life cycle. It discusses the importance of consistent nomenclature for external vendor data, emphasizing the interchangeable use of terms like vendor data, external data, and third-party data. The document details the external data life cycle, commencing with data collection and the subsequent phases, including validation, aggregation, analysis, and interpretation. A significant focus is placed on the challenges posed by the growing volume of external data sources, particularly in decentralized trials, which have led to increased end-of-study timelines and associated costs. The guide advocates for the establishment of clear data collection standards and effective communication strategies among cross-functional teams. Additionally, it highlights the necessity for robust data validation checks at multiple stages of the data flow to ensure compliance and accuracy, ultimately aiming to streamline the workflow from data ingestion to submission.