Air pollution and traffic congestion are common problems in Indonesia, especially in Jakarta. Mainly because the number of private vehicles increased rapidly in recent years, not only it resulted in traffic congestion, but also environmental problems and human health hazards because of its emissions. Transportation authorities have always been trying to find a way to reduce private vehicles and to encourage using public transportation. This study presents a conceptual model to understand Generation X and Generation Y's willingness to use public transportation in Indonesia. The model developed using an integrated model combining theory of planned behavior (TPB), technology acceptance model (TAM), environmental concern, and demographics. Transportation experts validated the research model through semi-structured interviews and questionnaires. Structural Equation Modelling (SEM) used to test variables in the next step. The results of this study could be useful to understand Generation X and Y's behavioral intention towards public transportation use.