Despite strong empirical support for treatments of eating disorders, research has demonstrated a trend of clinicians deviating from protocols outlined in empirically supported manuals. The present study used a convergent mixed-methods design to understand clinicians' use of and drift from empirically supported treatments in a sample of 114 licensed clinicians in the US who had substantial experience (i.e. one-third of caseload) working with patients with eating disorders and training in cognitive-behavioral therapy (CBT), family-based therapy (FBT), and/or interpersonal therapy (IPT) for eating disorders. Results revealed that 63.7-76.3% of clinicians drift from empirically supported treatments and 71.8% were aware they deviated from empirically supported treatments. Qualitative analyses identified client differences (57.2%) to be the primary reason why clinicians drift, with less participants describing therapist factors (20.4%), treatment shortcomings (12.6%), treatment setting (11.7%), logistic constraints (4.9%) and family factors (4.9%) as reasons why they drift. These findings suggest that drift for most clinicians may be better explained under the umbrella of evidence-based practice. Clinicians also identified a number of ways in which treatment and access to treatment can be improved. This broadened understanding of the use of empirically supported treatments within evidence-based practice may serve to help bridge the gap between research and practice.