This paper reports the development of a microsimulation model-building platform and the implementation, validation, and deployment of an integrated transportation and land use model using the platform. The modeling platform provides a new approach to microsimulation by providing modular algorithms with which models can be configured without additional coding, enabling the rapid development, testing, and deployment of models. The integrated transportation, land use, and energy (iTLE) model is an operational microsimulation model for Halifax, Canada, that combines long-term household decisions with short-term travel choices. The model’s longer-term decision simulator simulates life-stage transitions, residential mobility, and vehicle transactions. The residential mobility module uses a logsum measure of modal accessibility to capture how house-holds’ travel options influence their location decisions. The model was run from 2006 to 2036 on a business-as-usual scenario of land use and transportation. Validation performed after 10 years against census data indicates that the model produces a well-calibrated simulated population. The model predicts rising population density and greater household incomes in the urban core and a rise in vehicle ownership. The disaggregate nature, integration of land use and travel behavior, and life-course perspective of the modeling framework make it valuable as a decision-support tool for testing alternate scenarios against the baseline. The ease of development afforded by the modeling platform will facilitate future research on new mobility options, ensuring that the model can easily be adapted to anticipated transformational changes in the transportation system.