- "We can call ourselves the Diary Twins!"
- Rowley says to Greg after he gets a Diary on his birthday
Rowley's Diary was a "Sweet Secrets" Diary of Rowley. At his birthday in Rodrick Rules, he got a Diary from his parents because he asked them for it. The main reason he did it was because Greg had a diary and Rowley wanted to be like Greg so he asked for it. After receiving it, Rowley started recording Dinoblazer Action Figure matches in his diary. After teachers gave the kids a questionnare paper to know what jobs they may get, Rowley got "nurse" and he started hanging out with other girls who got "nurse". Soon Greg wanted to know what was all the gossip, so he bought another Sweet Secrets diary and stole Rowley's and opened it with his new diary's key. But Greg did not find any of the gossip as Rowley recorded page-by-page of Dino Blazer Action Figure matches, making Greg wonder why he is friends with Rowley.