Research in related fields that employ behavioral interventions indicates that factors common to treatment programs may be more important to successful outcomes than specific components of a treatment. Applying this concept to speech-language pathology, we investigated one hypothesized "common factor," namely, the clinician who implements treatment. Data were collected from limited samples of speech-language clinicians in two surveys. In Study One, 79 participants responded to open-ended questions about the nature of effective clinicians. A thematic analysis of their responses resulted in three broad categories of characteristics: behaviors, traits, and acquisitions. These themes were incorporated into an online survey for Study Two, in which 158 clinicians rated the importance of 25 clinician qualities. Their ratings suggested that the clinician-client relationship may be particularly important to treatment outcomes. These preliminary findings provide a foundation for further research on the clinician's contribution to treatment efficacy. Learning outcomes: Readers will be able to: (1) understand the concept of Common Factors; (2) describe the impact of clinicians on speech-language therapy outcomes as predicted by the Common Factors model; (3) list important characteristics of effective speech-language clinicians.