In chapter four, the four least powerful individuals on the ranch gather together in Crooks's secluded room attached to the barn. Crooks, who suffers from racial discrimination and is one of the loneliest people on the ranch, uses his power over Lennie to make him feel upset about the possibility of George leaving him. Instead of sympathizing with Lennie and treating him with respect, Crooks projects his negative feelings and emotions onto him and tyrannically wields his power. Despite his low social status on the ranch, Crooks is more intelligent and independent than Lennie, which essentially gives him more power. Crooks's cruel treatment of Lennie illustrates that power can be corrupting and change a person into a harsh, insensitive individual. After suffering from decades of oppression and discrimination, he uses his power to persecute Lennie, who struggles to defend himself against Crooks's arguments.

Likewise, Curley's wife also assumes the rare opportunity to be the most powerful person in the room when she enters Crooks's living quarters. She begins by criticizing the men about their hopeful dreams of one day owning a homestead, which upsets everyone in the room. When Crooks demands that she leave them alone, Curley's wife threatens to have him publicly hanged. Curley's wife has also suffered from years of oppression and discrimination. She is the only woman on the ranch and struggles under her husband's domineering control. However, in Crooks's room, she is the most powerful person and callously wields her authority. By threatening to have Crooks's hanged, Curley's wife not only projects her negative emotions onto Crooks but also illustrates once again that power is a corrupting force. In this chapter, Steinbeck is commenting on the psychological effects of living in America's difficult, challenging environment during the Great Depression and the corrupting nature of power.

This chapter brings together four misfits, outsiders both in the world of the ranch and in society at large. Crooks is a cripple and the only black man at the ranch; Candy is old and disabled; Lennie is intellectually-challenged and Curley's wife is the only female at the ranch.

Except for Lennie, who has George (and in any case is not aware enough to appreciate his isolated position in the world), all these characters suffer acutely from loneliness and frustration. However, when they all come together for one brief period in Crooks's room, we see that they do not all regard themselves as being on the same level. Their interaction and dialogue reveal the gradations of power that exist even in this one quartet of characters.

Crooks, for instance, taunts the slow-witted Lennie about George maybe not coming back; he briefly enjoys a sense of power which is generally denied him at the ranch because of his colour and disability. However, this is only temporary, and when Lennie physically threatens him, he has to retract.

In the main, Curley's wife feels and acts as though she is on a level above the others. She chafes at the fact that she has been left alone with the three weakest men on the ranch:

'An' what I am doin? Standin' here talking to a bunch of bindle stiffs - a nigger an' a dum-dum an' a lousy ol' sheep - an' likin' it because they aint nobody else'. 

Curley's wife here cruelly pinpoints the disadvantages that the three men suffer from. She is especially virulent towards Crooks, when he dares to assert himself briefly against her, and orders her to leave his room.  She reacts with anger, pointing out that she could easily have him lynched. At this vicious reminder of his racially subservient position, Crooks simply retreats into himself. As the only black at the ranch, he really has no power at all. Candy and Lennie are almost equally powerless, however. When Candy threatens to expose Curley's wife's attack on Crooks, she points out contemptuously that 'no-one'd listen to you' and Candy has to concede this is true.

In a way, then, Curley's wife has the upper hand of the other three, but at the same time she is aware that men in general at the ranch don't respond to her, and shut her out. Although she can make threats against a single black man, she really has no more power than do Crooks, Candy, and Lennie.