In 1942, Eastman was drafted by the Army and assigned to the Signal Corps film unit, which was headed by Theodor Geisel, who later became known as Dr. Seuss. Here, Eastman conducted picture planning for animated sequences in orientation and training films, and he also wrote scripts and drew storyboards for the Private Snafu series for Army-Navy Screen Magazine.
Eastman, a protégé and colleague of Theodor Geisel (pen name Dr. Seuss), wrote many books for children in his own distinct style. He worked with the Dr. Seuss brand of Random House, many of which were in the Beginner Books series. His titles include:
Big Dog...Little Dog (ISBN0-375-82297-6), 30th anniversary edition with additional story, words and illustrations by Peter Anthony Eastman (Beginner Book #92)
My Nest Is Best (ISBN0-375-83267-X) (Bright and Early Playtime Book)
The Alphabet Book (ISBN978-0-553-51111-6) (Random House Pictureback Book, later Bright and Early Book #41 (ISBN0-375-80603-2) with additional materials by Tony Eastman from the Bright and Early Board Book edition)
Big Dog...Little Dog: A Bedtime Story (ISBN0-394-83312-0) (Random House Pictureback Book)
Big Dog...Little Dog (ISBN0-375-87539-5) (Bright and Early Board Book with additional materials by Peter Anthony Eastman)
Aaron is a Good Sport (ISBN978-0-553-50842-0) (Step into Reading level 1) adapted from Everything Happens to Aaron in the Spring (Take Along Books)
Aaron Has a Lazy Day (ISBN978-0-553-50844-4) (Step into Reading level 1) adapted from Everything Happens to Aaron in the Summer (Take Along Books)
Aaron Loves Apples and Pumpkins (ISBN978-0-553-51234-2) (Step into Reading level 1) adapted from Everything Happens to Aaron in the Autumn (Take Along Books)
Aaron is Cool (ISBN978-0-553-51237-3) (Step into Reading level 1) adapted from Everything Happens to Aaron in the Winter (Take Along Books)
The Big Red Book of Beginner Books (ISBN978-0-375-86531-2) (I Want to Be Somebody New!: A Sequel to Put Me in the Zoo, Sam and the Firefly, Stop That Ball!, Robert the Rose Horse, The Very Bad Bunny, and The Digging-est Dog (1995, reprinted in 2010)
The Big Purple Book of Beginner Books (ISBN978-0-307-97587-4) (A Fish Out of Water, Snow, I'll Teach My Dog 100 Words, Flap Your Wings, Big Dog...Little Dog and Fred and Ted Go Camping (2012) (his last work after his death in early 1986)
Direct-to-video
The P.D. Eastman collection was a series released by Random House. They are a video version of a "book on tape". None of these productions are animated.
In 1941 Eastman married Mary Louise Whitham of Glendale, California. He had two sons, Alan Eastman and Peter Anthony (Tony) Eastman, an animator, who himself directed video adaptations of Richard Scarry's children's books. Peter has also written and illustrated Fred and Ted Go Camping (2005), Fred and Ted Like to Fly (2007), and Fred and Ted's Road Trip (2011), and contributed new illustrations to several reissues of his father's books, The Alphabet Book (2000), Big Dog... Little Dog (2003), Red Stop! Green Go! (2004), and The Cat in the Hat Beginner Book Dictionary (2007).