In a TIP approach policy experimentation is needed at all stages of transformation. This research briefing provides an overview of the various practices, rationales and approaches associated with experimentation and gives some examples in practice from TIPC member countries. These are termed ‘Experimental Policy Engagements’ (EPEs). It proposes that individual and a portfolio of EPEs can lever specific transformative outcomes, which connect to three processes of transformation: successful niche building, niche expansion and embedding, and destabilisation and opening up of socio-technical regimes. It proposes 12 ‘Transformative Outcomes’. The work itself is experimental and we plan to further develop the understanding and usefulness of the transformative outcomes by working in practice in a co-creation process with TIPC members. This briefing has been adapted from a longer report published by the authors in March 2019.