School counselor credentialing requirements have been a continuous topic of discussion for counselor educators and credentialing bodies. Recent discussions include whether or not prior teaching experience is needed to be an effective counselor. The authors surveyed over 300 school counselors from states with varied credentialing standards and asked them to respond to questions regarding perceived counseling effectiveness, collective self-esteem, and previous teaching and school counseling experience. The results indicate the most significant predictors of school counselor perceived effectiveness are their experience in school counseling and their collective self-esteem with the school counseling profession. Implications for school counselor education are discussed. (Contains 4 tables.)