While the Interagency Task Team on the Prevention and Treatment of HIV Infection in Pregnant Women, Mothers, and Children (IATT) partnership existed before the Global Plan Towards the Elimination of New HIV Infections Among Children by 2015 and Keeping Their Mothers Alive (Global Plan), its reconfiguration was critical to coordinating provision of technical assistance that positively influenced country decision-making and program performance. This article describes how the Global Plan anchored the work of the IATT and, in turn, how the IATT's technical assistance helped to accelerate achievement of the Global Plan targets and milestones. The technical assistance that will be discussed addressed a broad range of priority actions and milestones described in the Global Plan: (1) planning for and implementing Option B+; (2) strengthening monitoring and evaluation systems; (3) translating evidence into action and advocacy; and (4) promoting community engagement. This article also reviews the ongoing challenges and opportunities of providing technical assistance in a rapidly evolving environment that calls for ever more flexible and contextualized responses. The effectiveness of technical assistance facilitated by the IATT was defined by its timeliness, evidence base, and unique global perspective that built on the competencies of its partners and promoted synergies across program areas. Reaching the final goal of eliminating vertical transmission of HIV infection and achieving an AIDS-free generation in countries with the highest HIV burden requires that the IATT partnership and technical assistance remain responsive to country-specific needs while aligning with the current programmatic reality and new global goals such as the Sustainable Development Goals and 90-90-90 targets.