The story revolves around youth culture, and particularly the gang culture of the Greasers, which has specific codes that its members must follow. The story also rests on broad class conventions in its portrayal of the clash between the rich Socials, known as Socs, and the Greasers who come from poorer backgrounds. These factors dictate much of the characters' behaviour and help drive the plot.
The Socs and Greasers are shown to be distinct youth sub-cultures; they occupy different territories and follow different fashons, and come together usually only in violent confrontation. This social and also cultural gap between the two is never really bridged in this novel, although, importantly, Ponyboy does come to understand that the Socs, too, have their own problems as the Greasers have theirs. Cherry, the rich Soc girl, provides something of a link between the two communities as she becomes friendly with Ponyboy and they talk about their similarities and differences. Ponyboy realises that the Socs and Greasers really aren't that different after all, they're all human. This understanding that only social conventions separate the two groups, forms a vital part of Ponyboy’s coming to maturity, which in turn is an important facet of the novel as a whole. However, a true reconciliation between the two sides is not really shown in this novel.
Being in the Greaser gang means a lot to Ponyboy. It's the only way of life he really knows, and it is his family - quite literally his family as his two older brothers, Soda and Darry are also firm members. The gang code of loyalty is a vital one for them all to follow. Despite some individual differences, the gang all stick together. This still doesn't mean that they can't have fallings out amongst themselves, but even here, a strict code has to be observed. One example of this is when Dally, the most unruly of the gang, starts harassing Cherry in the cinema. Johnny intervenes and tells him to leave her alone. Dally's reaction is as follows:
Dally scowled for a second. If it had been me, or Soda, or Two-Bit, or Steve, or anyone else but Johnny, Dally would have flattened him without a moment’s hesitation …. But Johnny was the gang's pet, and Dally just couldn't hit him.(chapter 2)
Even mean, tough Dally, then, strictly follows the gang's rules, which prevents him from laying a finger on Johnny at this point. At the other end of the spectrum, Darry, who generally leads quite a respectable and hardworking life, and always lectures Ponyboy on doing the same, finds it necessary to make time for the rumble, the big fight between the Socs and Greasers. The gang is an essential part of the Curtis brothers’ lives.