Mrs. Franklyn B. Sanders took over the directorship in 1926. Pianist Arthur Loesser joined the faculty that year. The first Preparatory branch opened in 1927 at 2789 Lancashire Road in Cleveland Heights. "Too much importance cannot be placed upon the foundation of musical education. Children's courses, where the child is taught from the first steps through the preparatory and intermediate grades, form an important part of the courses offered at the Institute." Later, the Heights Branch was located at Cedar Road and Fairmount Boulevard, the Lakewood Branch at 15614 Detroit Avenue and the Brooklyn Branch at 3804 West 25th Street.
The School of Opera with Marcel Salzinger as director was instituted in 1927 to "give singers in this country the advantages of operatic training and experience." The Cleveland Plain Dealer said, "The Cleveland Institute of Music had a big surprise for its friends in the genuinely successful operatic performance of Cavalleria Rusticana." The Cleveland Press advised, "The demands of grand opera are numerous and exacting, but no detail had been overlooked ... the Institute has reason to be proud of the success of the School of Opera."
The 1930s continued the Institute's success. Beryl Rubinstein took the helm in 1932, and the school moved into its new quarters in June in the Samuel Mather House at 2605 Euclid Avenue. Alice Chalifoux, harp, was now on the faculty and concertizing. The Annual Program of Music by Cleveland Composers featured works by Quincy Porter and Herbert Elwell, both on the CIM faculty. The Cleveland Trio, comprised of Beryl Rubinstein, piano; Josef Fuchs, violin; and Victor de Gomez, cello, performed regularly. The CIM Women's Committee, raising funds through benefit events and other musical programs (now one of the largest donors to CIM's Annual Fund), was formed in 1933. Mrs. George P. Bickford was the first president.
Upon Mr. Rubinstein's leave of absence in 1935, Mr. Elwell was appointed assistant director. The fifteenth season celebrated with 600 students and a faculty of 40. Boris Goldovsky was named head of the opera department in 1936, and the season of lectures, recitals and concerts numbered 50. Preparatory students composed a three-act operetta to the story of "Cinderella" and entertained 1,400 concertgoers in April 1937.
A Bachelor of Music degree student paid $175 per semester in 1938-39 with lessons ranging from $1.50-$6.00. Percy W. Brown was president of the board of trustees of the college, which was a charter member of the National Association of the Schools of Music.