Assessing treatment integrity is essential to understanding how well school-based interventions are delivered. The assessment of treatment integrity is especially challenging for interventions that provide one-on-one peer support over the phone. To address this gap, we explored treatment integrity approaches used for the "Parent Connectors" program, which provides parent-to-parent support via weekly phone calls to families of students receiving special education services for emotional and behavioral disturbance. Our multi-dimensional approach to assessing treatment integrity includes the consideration of dose, adherence, quality of service delivery, participant responsiveness to the intervention and program differentiation. We share and discuss data from a variety of approaches that have been used with this intervention to collect treatment integrity data such as logs completed by the trained parents following each phone call, content ratings of behavioral rehearsals between trained parents and research staff and surveys regarding services received from participants. We discuss obstacles collecting treatment implementation data, ways our approach is continually evolving and possibilities of applying some treatment integrity approaches to wide-scale intervention applications in the field. [This is the online version of an article published in "School Mental Health."]