evidence: The Teenage Pregnancy Strategy (TPS) was the first comprehensive approach by any UK government to reduce England’s high teenage pregnancy rates. The rate had been, for many years, higher than other western European countries and outcomes for young parents and their children were disproportionately poor. The strategy was launched in 1999 with a goal of halving the under-18 conception rate. By 2014, the rate had dropped 51% [1]. The purpose of this study was to explore how the strategy was designed and implemented to achieve its success. This paper complements two previously published articles. The first [2] presents an overview of the strategy within the WHO ExpandNet framework; the second [3] confirms the impact of the strategy by combining detailed analysis of the outcomes along with the data from the Natsal-2 and Natsal-3 studies. Although there is inevitably some overlap of material, this new paper provides significantly more detail, serving to illustrate the complexities involved in implementing a strategy that achieved such a high level of change, refers how to access key documentation, and identifies six key features which were fundamental to its success.