Methods and systems for configuring a modular building control system. An illustrative method may include entering a configuration mode in a base module and in each of the expansion modules. While in the configuration mode, the base module may collect information from each of the expansion modules. A system configuration may be created for the modular building control system based at least in part on the collected information and includes configuration parameters for the base module and each of the expansion modules. The base module may transmit to each of the expansion modules their respective configuration parameters. The base module and each of the expansion modules may install their respective configuration parameters, exit the configuration mode, and enter an operation mode. While in the operation mode, the base module and each of the expansion modules may control the modular building control system.