Effective support for children with developmental disabilities or delays is dependent on the successful collaboration between families and professionals and among professionals. For years, researchers and professionals have been coaching caregivers and other professionals to implement evidence-based practices with children with disabilities. However, a gap in the relevant literature suggests that a valid, reliable, and observation-based measurement tool is needed to accurately assess coaching across different disciplines, contents, and contexts. The Coaching Fidelity Scale (CFS) was designed to evaluate the extent to which professionals implement a set of coaching practices with fidelity. The purpose of this exploratory study was to introduce the CFS as an observational tool for coaching fidelity and to pilot its psychometrics. On the basis of the analyses, the CFS produced valid and reliable measures of coaching fidelity of different professionals who provide services to families and children with disabilities.