his paper presents a broad perspective on traffic flow modeling at a spectrum of four scales. Modeling objectives and model properties at each scale are discussed and existing efforts are reviewed. In order to ensure modeling consistency and provide a microscopic basis for macroscopic models, it is critical to address the coupling among models at different scales, i.e. how less detailed models are derived from more detailed models and, conversely, how more detailed models are aggregated to less detailed models. With this understanding, a consistent modeling approach is proposed based on field theory and modeling strategies at each of the four scales are discussed. In addition, a few special cases are formulated at both microscopic and macroscopic scales. Numerical and empirical results suggest that these special cases perform satisfactorily and aggregate to realistic macroscopic behavior. By ensuring model coupling and modeling consistency, the proposed approach is able to establish the theoretical foundation for traffic modeling and simulation at multiple scales seamlessly within a single system.