With the exception of the additional cast member, Scooby-Doo and Scrappy-Doo stuck to the tried and true Scooby-Doo format during its initial season. Teenage friends Fred, Daphne, Velma, Shaggy and their more-friend-than-pet, a Great Dane by the name of Scooby-Doo, couldn't resist solving mysteries, which they came across with unsettling regularity. That is, all except Shaggy and Scooby felt compelled to solve mysteries. The two were much too cowardly for that type of pastime, but being outvoted three to two meant they had to face their fears on a regular basis. What appeared to be supernatural occurrences involving ghosts and monsters the gang was always able to expose for the shams they were; attempts by unscrupulous individual using special effects and costumes to scare away others in order that their crimes could succeed.

The gang was led by Fred, who also drove their green colored van, the Mystery Machine. When the group split up while investigating in order to cover more ground, which they invariably did, fashionable Daphne and brainy Velma normally went with Fred, while the team of Shaggy and Scooby went their own way. When Scooby-Doo joined the team his boundless courage and scrappy attitude were in direct contrast to his uncle Scooby, who he looked up to and believed was every bit as fearless as himself, even though all evidence pointed to the contrary. When Scrappy-Doo saw danger, he went charging in with the call of, "Ta-da-da-tut tut-tah, Puppy Power!" But before his reckless abandon could get him into serious trouble, Shaggy and Scooby would grab him and drag him away in their own headlong flight to safety. Scrappy had a way of finding himself in the thick of the action anyway, but as usual the gang's resident bookworm, Velma, was the first to put the clues together and solve the mystery.