Frank Caplan was a youth worker, educator, folk toy collector, and pioneer in developing and manufacturing educational toys for children. He co-founded Creative Playthings in 1945 with his wife Theresa, and worked with artists, architects, and designers, such as Isamu Noguchi, Louis Kahn, Henry Moore, Robert Winston, and the Swiss toymaker, Antonio Vitali, to create innovative educational play objects and playground designs for children. 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. In 1975, Frank Caplan founded The Princeton Center for Infancy and Early Childhood. He researched and co-authored a national bestselling series on early childhood development with Theresa Caplan, which included, 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). Together they also co-authored The Power of Play (1973). He was one of the first male nursery school teachers in the U.S. and together with Theresa Caplan collected over 50,000 American and international folk toys, folk art, and contemporary playthings, which in 1984 the couple donated to The Children's Museum of Indianapolis for a permanent gallery on folk, fantasy, and play.