Through an extensive literature search and two rounds of pilot studies, a team of academics, NPDES permittees, and on-the-ground experts developed effectiveness metrics for the evaluation of rain garden/bioretention functionality. Through this process the team developed an assessment protocol. This framework also provides insight into how installation methods and maintenance practices effect functional success of bioretention facilities and rain gardens. The effectiveness metrics include soil and probable infiltration characteristics, bypass/overflow attributes, plant viability, public acceptance, maintenance issues, and whether the installation is still collecting runoff. This presentation will provide an overview of the metrics, data methodology, protocol limitations, challenges and successes, as well as an overview and interpretation of the results from 41 assessed sites. It will also outline how jurisdictions and others can access and adapt the protocol for their use.