The Jefferson Family is a wealthy family in Greg's neighbourhood. Not much is known about the Jefferson Family, the only known extended family members are Grandpa Jefferson, Rowley's Cousins and an unnamed uncle of Rowley mentioned in The Long Haul.
- Linda Jefferson-Mother of Rowley, Wife of Robert
- Robert Jefferson-Father of Rowley, Husband of Linda
- Rowley Jefferson-Only Child
- Grandpa Jefferson-Robert's Father
- Rowley's Cousins-The cousins of Rowley, the nephews of Linda or Robert.
- Unamed uncle of Rowley-Lives in Asia.
Notice: The appearances are counted only if all the members of at least the nuclear family have appeared.
- Diary of a Wimpy Kid Online (First appearance)
- Diary of a Wimpy Kid
- Diary of a Wimpy Kid: Rodrick Rules
- Diary of a Wimpy Kid: Dog Days
- Diary of a Wimpy Kid: Cabin Fever
- Diary of a Wimpy Kid (film)
- Diary of a Wimpy Kid: Dog Days (film)
- Out of the family, only Rowley Jefferson appeared in all the books, however his father also appeared in all books until Hard Luck.
- In Cabin Fever, Greg says that Rowley is unfamiliar with the church's rules as his family doesn't visit it regularly.