These children’s book series feature siblings and cousins who solve mysteries together.
Siblings
A family with four children, two sets of fraternal twins, solves mysteries together. A Stratemeyer Syndicate series. 1904-1992.
Four children who lived alone in a boxcar after the death of their parents are taken in by their grandfather and solve mysteries everywhere they go. 1924, 1942-Present.
Flee Jay and Clarice Mysteries
About a girl who wants to be a detective and her genius younger sister. By Carol Farley.
Hardy Boys Mysteries
Two brothers, Frank and Joe Hardy, solve mysteries in their East Coast town of Bayport and around the world. By Franklin W. Dixon, A Stratemeyer Syndicate series. 1927-Present.
About three siblings who solve mysteries together. Many of them are treasure hunts. By Peggy Parish.
Mary Rose and Jo-Beth Mysteries
About a pair of sisters who live in Indiana and have adventures on road trips with their father. Not all of the books in the series are spooky mysteries, but a couple are. Written by Eth Clifford.
The stories all take place in the fictional town of Morgan Bay. Originally used as classroom readers.
A widow with five children turns her family into a band, and they travel around to singing engagements in a bus painted with psychedelic designs, having adventures along the way. Book series based on the tv show. The tv show wasn’t about mysteries, but I put the book series here because many of the books are mysteries.
Sam and Dave Bean are a pair of twin boys who solve mysteries with their friends. Most of their mysteries center around people they know from school.
The Stanleys are a blended family, and the children solve mysteries, sometimes with a spooky theme. The best known book in the series is The Headless Cupid. By Zilpha Keatley Snyder.
Ryan and Chris Taylor are a pair of thirteen-year-old fraternal twins who solve mysteries. They can sense each other’s thoughts. By Adam Mills. 1988-1989.
Cousins
A pair of teenage cousins solve mysteries. 1966-1986.
Three cousins, Timothy, Titus, and Sarah-Jane, solve mysteries together. The books have Christian themes. By Elspeth Campbell Murphy.
Jestress's Forgotten Books and Stories 