This paper addresses the problem of interactively modeling large street networks. We introduce a modeling framework that uses tensor fields to guide the generation of a street graph. A user can interactively edit a street graph by either modifying the underlying tensor field or by changing the graph directly. This framework allows to combine high- and low-level modeling operations, constraints, and procedural descriptions. CR Categories: F.4.2 [Mathematical Logic and Formal Languages]: Grammars and Other Rewriting Systems I.3.5 [Computer Graphics]: Computational Geometry and Object Modeling I.3.7 [Computer Graphics]: Three-Dimensional Graphics and Realism I.6.3 [Simulation and Modeling]: Applications J.6 [ComputerAided Engineering]: Computer-Aided Design (CAD)