While central business districts (CBDs) are the economic engines of regions across the country and host employment centers, housing, retail, and services, limited information is available to planners and public officials regarding how people access these areas. This report documents a study undertaken by the Boston Region Metropolitan Planning Organization (MPO) to understand the modes of transportation customers use to access a selection of CBDs in the Boston region. In this study, MPO staff identified and classified the CBDs of the 97 municipalities in the Boston region. Staff distributed a survey to business owners regionwide asking for the owner’s perception of customers’ travel and spending patterns. Staff selected a sample of CBDs for further study. In these locations, staff distributed a survey in-person to customers at participating businesses. Staff compared travel patterns reported by customers, including mode splits, with merchants’ perceptions. Staff also collected summary data on curb-lane designations to understand how access to curb space might affect customer mode choice. The report found that mode choice varies according to a number of factors—including the density of the municipality, business type, time of day, and day of the week—and that additional data collection would be necessary to support municipal and stakeholder decision making.