Beginner Books is the
Random House imprint for young children ages 3–9, co-founded by
Phyllis Cerf with Ted Geisel, more often known as
Dr. Seuss, and his wife
Helen Palmer Geisel. Their first book was
Dr. Seuss's
The Cat in the Hat (1957). Cerf compiled a list of 379 words as the basic vocabulary for young readers, along with twenty more slightly harder "emergency" words. No more than 200 words were taken from that list to write
The Cat in the Hat. Subsequent books in the series were modeled on the same requirement.