This study presents a historical perspective of the education of music therapists in the United States in the 1960s-1970s and addresses the innovative aspects of music therapy advocated by the National Association of Music Therapy (NAMT). First, relevant articles published in The Journal of Music Therapy are examined to clarify NAMT's concept of music therapist education. Secondly, practical examples proposed in the books Music in Therapy (MT) and Therapy in Music for Handicapped Children (TMHC) are explored to illustrate the practices of music therapy current in the United States in the 1960s. NAMT successfully extended its clinical modalities by incorporating behavioral psychology practices. This scientific approach is highly appreciated in MT, whereas it is not as significantly valued in TMHC. This ideological difference triggered an erosion of solidarity among the members of NAMT, which eventually lead to the establishment of two independent academic conferences in the early 1970s. The author concludes from the present survey that: (1) music therapy enjoyed the scientific benefits of behaviorism in the 1960s, and (2) this led to the formation of two distinctive streams of philosophy of music therapy in terms of perspective and methodology.