One year after the events of Grown Ups 2, Lenny, Kurt, Marcus and Eric decide to bring their families to a campground for the summer. Things seem to be going along very well. However, things get bad when Frat Boy Andy and his crew returns from the previous film and attempt to get revenge on the gang for what they did in the last film. The trio then decides that it is time to put an end to the Frat Boys in this final installment to a successful franchise.
- Adam Sandler as Lenny Feder
- Chris Rock as Kurt McKenzie
- David Spade as Marcus Higgins
- Kevin James as Eric Lamonsoff
- Salma Hayek as Roxanne Feder
- Taylor Lautner as Frat Boy Andy
- Steve Buscemi as Wiley