Lichtenstein returned home to visit his dying father and was discharged from the army with eligibility for the G.I. Bill. He returned to studies in Ohio under the supervision of one of his teachers, Hoyt L. Sherman, who is widely regarded to have had a significant impact on his future work (Lichtenstein would later name a new studio he funded at OSU as the Hoyt L. Sherman Studio Art Center).
Lichtenstein entered the graduate program at Ohio State and was hired as an art instructor, a post he held on and off for the next ten years. In 1949 Lichtenstein received a Master of Fine Arts degree from the Ohio State University.
In 1951 Lichtenstein had his first solo exhibition at the Carlebach Gallery in New York. He moved to Cleveland in the same year, where he remained for six years, although he frequently traveled back to New York. During this time he undertook jobs as varied as a draftsman to a window decorator in between periods of painting. His work at this time fluctuated between Cubism and Expressionism. In 1954, his first son, David Hoyt Lichtenstein, now a songwriter, was born. His second son,Mitchell Lichtenstein, was born in 1956.
In 1957, he moved back to upstate New York and began teaching again. It was at this time that he adopted the Abstract Expressionism style, being a late convert to this style of painting. Lichtenstein began teaching in upstate New York at the State University of New York at Oswego in 1958. About this time, he began to incorporate hidden images of cartoon characters such as Mickey Mouse and Bugs Bunny into his abstract works.