The authors argue that implementation research requires its own set of outcome measures to understand whether evidence-based interventions are successfully adopted and sustained in practice. They introduce a taxonomy of eight implementation outcomes: acceptability, adoption, appropriateness, feasibility, fidelity, implementation cost, penetration, and sustainability. These outcomes are conceptualised as distinct from service quality outcomes and patient clinical outcomes, while also serving as important precursors to both. Overall, the paper provides one of the most influential frameworks in implementation science and has played a central role in standardising the evaluation of implementation efforts across healthcare and mental health settings.