The successful acceptance of traffic microsimulation software depends crucially on the verification and validation (V&V) procedures for testing the core behavioral algorithms. These must be sufficient to convince researchers, software developers, and practitioners that the algorithms are accurate and robust. V&V procedures must also be well documented to ensure public acceptance. A suggested V&V procedure is presented. The central theme is that verification and validation are integral parts of the entire algorithm development process. A three-stage algorithm development and V&V procedure for traffic microsimulation algorithms is recommended. Algorithm development includes identifying key variables and setting model parameters. Next, the software implementation of the algorithm is tested during the algorithm-level testing stage with a combination of hypothetical and simple real-world data. Finally, system-level testing of the algorithm software is done within a complete microsimulation modeling system. In the last stage, the system with the new algorithm is tested against complex real-world data sets.