Research has demonstrated that participation in parent and child therapy (PCT) programs significantly reduces problematic behaviors while increasing positive behaviors in the child. However, PCT programs report rates of early termination as high as 60% among families in poverty. Research to reduce these early termination rates has historically focused on barriers to treatment including logistical conflicts, socioeconomic status, child age, and symptom severity. Despite attempts to address these variables and reduce early termination rates, progress has been slow in advancing the research in this area. In addition, few measures have been designed to accurately assess how barriers to treatment impact treatment attendance and participation, particularly for families of young children living in poverty. The purpose of this study was to develop and pilot a clinician-report screening tool, the Treatment Barriers Scale (TBS), to assess barriers to treatment participation in primarily low-income, urban minority families receiving home-based therapy for their young child’s challenging behaviors. Data from 330 families consecutively referred to a mental health clinic for behavior problems were analyzed to identify the initial psychometric and predictive properties of this new tool in screening treatment barriers in this population. The resulting 17-item scale consisted of two factors, labeled Treatment Process Barriers and Operational Barriers. Each factor demonstrated acceptable levels of internal consistency (.82 and .80, respectively). Children with more-severe challenging behavior at pretest were more likely to be successful by the third session in treatment. Families with higher TBS scores were more likely to be less successful early in treatment. Limitations of the study and implications for future research and practice were discussed.