Labeling Theory
Labeling Theory explains how the identity and behavior of people are influenced by how society has classified them. According to the Labeling Theory, an individual who commits actions that are frowned upon by society, becomes regarded as a criminal or a deviant only when he is labeled as such. For some people, being labeled as a deviant actually encourages them to behave in ways that are consistent with the label.
For example, a teenager who is caught cutting class and labeled as a delinquent, may be less motivated to attend class, thinking that there's no point in making an effort to attend class as no one expects him to be there anyway. Having skipped class, he is then unaware of assigned homework, and so fails to turn in his assignment, thus propagating the idea of being a delinquent student.