Conformity is a motif of To Kill a Mockingbird. 

In the essay entitled "Self-Reliance" in which Ralph Waldo Emerson rails against imitation, he writes that conformity is a game of "blind-man's bluff"; furthermore, he states that in demanding conformity,

society everywhere is in conspiracy against the manhood [individuality] of every one of its members.

Certainly, Emerson's convictions about conformity hold true in several instances of the narrative of Harper Lee's novel.

In the realm of education, there are instances in which conformity exemplifies a certain blindness to the true goal of learning. For example, in Chapter 2 when Scout attends school on the first day, Miss Caroline becomes upset with her because she already knows how to read. Scout's reading proficiency disturbs the proper order of learning to which Miss Caroline adheres. So, when Scout demonstrates competency by reading easily

...most of My First Reader and the stock-market quotations from The Mobile Register,

Miss Caroline instructs her nonsensically to tell her father to discontinue his teaching because "it would interfere with [her] reading." What she really means is that Scout's advanced skill does not conform to the expectations of first grade and the precepts of educational theorists she has studied. Since Miss Caroline only knows how to teach by conforming to these precepts, Scout must be on a similar level with the other students.

As a lady of Maycomb's society, Aunt Alexandra adheres to a certain way of dressing on Sundays and at social gatherings. In preparation for her tea with the ladies of the church, she insists upon making the refreshments herself. Scout is forced to wear a dress and to conduct herself as a lady at this tea. 

In another example of conformity, frequently Alexandra speaks to her brother Atticus about his methods of parenting and the close relationship of Calpurnia and the children, all of which do not adhere to conventional norms for their social class.

Considered the most egregious break from social conformity in Maycomb is the acceptance of the role of defender of Tom Robinson by Atticus. His role as the defense attorney for Tom Robinson, a black man, brings upon Atticus vile name-calling and actions that threaten his safety (e.g. the mob appears at the jailhouse where Tom is kept before the trial).
The Idler's Club disparages Atticus because, as one man says, he "thinks he knows what he's doing." Another man complains of Atticus's non-conformity because he "aims to defend him [Tom]."

Before the trial of Tom Robinson begins, the children see Mr. Dolphus Raymond, who has been ostracized from white society for not conforming to unwritten rules of Maycomb society. He has mixed-race children, and he lives in the black community.

Perhaps the strongest conformity is that of the twelve men on the jury. Despite Atticus's leaving doubts in the minds of the jury about the credibility of the testimony of Bob and Mayella Ewell, as well as the lack of any positive evidence, eleven of the all-white male jurors conform to the conventional thinking of the Jim Crow South by handing down a verdict of guilty against the black Tom Robinson. Only one man, a Cunningham, votes otherwise.