[1] By the 1950s, Creative Playthings had gained international recognition and expanded to become one of the most important manufacturers and suppliers of materials for early childhood education.

After graduating in 1931 with a bachelor's degree in sociology and history, he took a job as the director of the Block Recreation Project, working with street gangs to create club centers for leadership training.

Later, he worked at the Jewish Center in Far Rockaway, Long Island (along with his future wife, Theresa Caplan, and artist, Mark Rothko), where he made puppets and simple playthings for children.

[3] In 1975, Frank and Theresa Caplan co-founded The Princeton Center for Infancy and Early Childhood, a pioneering organization that researched and prepared books and pamphlets for parents and professionals.

Frank and Theresa co-authored The Power of Play (1973), The First Twelve Months of Life (1977), The Second Twelve Months of Life (1978), and The Early Childhood Years: The 2 to 6 Year Old (1983), which covered the mental, physical, language and social development of early childhood with advice for parents and answers to common concerns.