Why did George shoot Lennie at the end of the story?

George and Lennie are the two main characters in John Steinbeck's novella Of Mice and Men. The two men are traveling through depression era California as migrant farm workers. Lennie is mentally challenged and is, in many ways, a burden to George. He is also a very large and strong man who often does not realize his own strength.

At the beginning of the novel George makes reference to the problem he and Lennie faced...

George and Lennie are the two main characters in John Steinbeck's novella Of Mice and Men. The two men are traveling through depression era California as migrant farm workers. Lennie is mentally challenged and is, in many ways, a burden to George. He is also a very large and strong man who often does not realize his own strength.

At the beginning of the novel George makes reference to the problem he and Lennie faced in the town of Weed when Lennie tried to touch a girl's dress:

“Jus’ wanted to feel that girl’s dress—jus’ wanted to pet it like it was a mouse—Well, how the hell did she know you jus’ wanted to feel her dress? She jerks back and you hold on like it was a mouse. She yells and we got to hide in a irrigation ditch all day with guys lookin’ for us, and we got to sneak out in the dark and get outa the country. All the time somethin’ like that—all the time."

George is understandably leery of what Lennie might do, so he tells him that if he once again finds himself in trouble to return to the spot in the woods which is the opening setting of the book and "hide in the brush."

As the plot develops we meet several more characters, including the old swamper, Candy, whose dog is old and decrepit. One of the working men suggests that Candy put the dog out of its misery, but Candy doesn't have the heart to kill the dog he raised from a puppy. Instead he lets Carlson shoot the dog. The scene is significant because, in an example of foreshadowing, Candy tells George that “I ought to of shot that dog myself, George. I shouldn’t ought to of let no stranger shoot my dog.”

As George expected, Lennie once again gets in trouble, but this time it is far more serious as he accidentally kills Curley's wife. Before Curley and the other men set off to apprehend Lennie, Slim warns that Lennie will not understand the consequences of his actions nor the animosity which Curley feels for him. Slim says,

"But Curley’s gonna want to shoot ‘im. Curley’s still mad about his hand. An’ s’pose they lock him up an’ strap him down and put him in a cage. That ain’t no good, George.” 

Even before hearing Slim's analysis of the situation, George has decided the best course of action regarding his friend. He has taken Carlson's gun and plans to shoot Lennie. As Candy suggested, George does not want a stranger killing his friend. In the final chapter George indeed shoots Lennie in the same spot that is the setting of the first chapter.

It may seem a harsh reality today that George had to kill his friend, but in the 1930's there was very little sympathy for those with Lennie's disability. Had Lennie been captured he would have been locked up and treated very poorly, something he certainly would not have understood. In fact, Lennie totally forgot what he had done. He simply knew that he had "done another bad thing" and George was going to "give him hell."