<Tr> <Th> Publisher </Th> <Td> Blue Sky (US), Scholastic (US) </Td> </Tr> <Tr> <Th> Published </Th> <Td> <P> September 1, 1997 - August 25, 2015 (main series) </P> (spin - offs from 2002 - present) </Td> </Tr> <P> September 1, 1997 - August 25, 2015 (main series) </P> <Tr> <Th> Media type </Th> <Td> Print (hardcover and paperback) </Td> </Tr>

When did the captain underpants books come out