Abstract: Transantiago, the public transport system implemented in Santiago, Chile, remains a controversial subject of public debate due to constantly increasing fare evasion rates throughout its decade-long existence. The research question under consideration in this paper is what motivates individuals to evade or pay bus fares. To answer this question, we developed a multidisciplinary study that combined relevant engineering expertise with a sociological perspective and combined quantitative analyses with qualitative methodologies to include new variables and categories that previous studies on the subject have omitted. We formulated a survey, which was administered to 503 public transport system users. The data we obtained were analyzed using a factor analysis. As a result, six dimensions were identified that explain motivations for fare evasion: (1) behavior and social norms, (2) the public transport service´s image, (3) social acceptance of evasion, (4) trip planning, (5) anti-evasion methods, and (6) fear of law enforcement.