ABSTRACT Evidence-based clinical interventions are often delivered with poor fidelity and abandoned by practitioners soon after training. In response to these findings, we have worked with practitioners and clients to co-design an automated decision support tool supporting Problem Solving Treatment (PST) for depression. PST-Aid is a web- based app that promotes practitioner–client collaboration in the use of PST for goal setting and action planning, which we conceptualize as an educate and reorganize implementation strategy. We propose to further redesign PST Aid by working with stakeholder groups from our partnering OCHIN health informatics network, which includes >300 independent community health centers across 45 states serving >130,000 unique clients monthly. We will conduct a hybrid type III effectiveness-implementation randomized clinical trial comparing standard PST implementation with PST implementation augmented by the PST-Aid implementation strategy. We will test whether: 1) PST Aid results in improved implementation outcomes (initial and sustained fidelity, adoption, reach, and reduced reactive adaptations); 2) changes in usability, engagement, and appropriateness mediate the effect of PST Aid on implementation outcomes; and 3) PST Aid is more effective in reducing client depressive symptoms and improving functioning. We will train 60 practitioners from 20–30 OCHIN clinics in PST, and then randomly assign them training in PST- Aid vs PST as Usual. We will recruit up to 350 clients with elevated depressive symptoms (PHQ-9>10), or an average of 5–6 per each practitioner trained in PST. Client and practitioner-centered decision-support tools embedded in electronic health records such as PST Aid have the potential to enhance appropriateness, engagement, and usability of evidence-based interventions. The ability of such tools to support fidelity to elements of clinical interventions like PST, while at the same time reducing burden, would represent a major step forward for the delivery of care and would have implications for a range of effective but seldom used interventions.