The Greasers are the group of teens (some a little older) from the poor, east side of town. The are usually blamed for any trouble that occurs and have an overall bad name in town. The rich, west side kids are known as the Socs, which is short for "Socials". Although these teenagers are as much to blame for bad doing in the town as the Greasers, they are put on a pedestal because they are the rich kids from "upstanding" families unlike the Greasers who are from less reputable families. These two groups of teens do not get along at all and their disagreements are often the cause of their rumbles.
The major event that takes place in Chapter 4 is the murder of Bob (a Soc) by Johnny (a Greaser) after Bob tries to drown Johnny's best friend, Ponyboy.