The researcher convinced that Mason Evans Jr. has to have gone through the periods of development over the course of his growth along with the personality traits or behaviors throughout the story of Boyhood film. By using Petrie and Boggs’ methods of characterization, the analysis focused on the depiction of Mason’s characteristics throughout his growth in order to determine the proper types of Mason’s character, which then also aimed to identify Mason’s periods of development alongside its criteria, in order to reveal the similarity with the periods from Erikson’s stages of development theory. The qualitative data used in this research were in forms of speech, dialogue, and scenes related to the characterization of Mason in Boyhood film. The results of the analysis are divided into two sections. The first section of the results shows that Mason can be concluded as an easily predictable character with his simple-minded and honest traits along with the sense of irresponsibility, while also undergoes the changes in his personality traits or behavior that caused by the choices of his own interests or purposes of the future. The second section of the results shows that Mason is within the periods of “Middle Childhood” and “Adolescence” throughout his yearly growth from six years old to eighteen years old throughout the course of the film’s story. Therefore, this research concluded that Mason’s character can be categorized within the types of flat-dynamic character; and the criteria of Mason’s period over his yearly growth are similar to the periods of “School Age” and “Adolescence” from Erikson’s theory of stages of development.