This chapter reviews the key implementation steps and outlines the key aspects to be considered and monitored, as well as key requirements to comply with throughout the execution phase, from sites selection to reporting of results. Beside a 'well-designed' protocol, the site selection process is probably one of the most challenging and critical steps of the project, as the performance of sites. Site monitoring requires on-site visits to be conducted by well-trained study personnel. Inspections to confirm Good Clinical Practice (GCP) at investigator sites have been occurring for many years. The steps followed to complete a routine close out of a study are delineated in 'Routine study closure' and are the same things that need to be completed in the event of early termination. Reporting the results of clinical trials is not just the publication of a peer-reviewed manuscript. There are several important parts, each serving different purposes.