This book is written by a boy that explains his childhood. The story happens in some USA village because they celebrate Thanksgiving day. His family consists of his parents and two brothers, one is older than him, Rodrick, and the other is younger Manny.He doesn´t get on well with his brother Rodrick and he is worried because Rodrick knows about the journal so he has to be sure he locks up it. As regards his youngest brother Manny he thinks he is very protected by his parents and he would like sometimes to hit him. The book starts in summer time when his family aren’t going to any special place and he has to go to the swimming pool because his father wants him to join the swimming team. He tells about the swimimming lessons in an ironic way and about how he tries to skip the lessons going to the toilet and getting frozen.
He has a friend called Rowley who has travelled during his holidays and he gets mad because he is always telling him about the trips. Rowley celebrates his birthday in a mall and he invites seven year old boys, something that Greg doesn´t find very funny. He complains Rowley is always doing the same things he does and about he was even bought a diary for his birthday.
School starts and he talks about his teachers. He had a Career Day which is a day kids must think about their future. He had to fill in some questionnaires and finally it turned oout he would be a clerk. This is not what he wishes because he was supposed to become a millionaire.
But one of the funniest chapters is when Greg and his brother Rodrick stayed one night alone without their parents and Rodrick, who has a flu, decides to throw a party. Greg goes to the basement to look for some chairs and gets locked. He spends all the party in the basement but the next morning he has to help Rodrick clean the house.
Although Rodrick is always bugging him at the end of the book he recognized he loves him because he is his brother and he offers his help to do the Science project.