Arlington Regional Transit (ART) and Washington Metropolitan Area Transit Authority (WMATA) operate fixed routes and demand response service throughout Arlington County, a compact urban county adjacent to the District of Columbia. Foursquare ITP managed the project and led the technical components of the County’s TDP, including assessments of the county’s demographic indicators and transit needs of the current service area using our multi-variable transit propensity tool and travel flows from the regional travel demand model. Our work included a detailed evaluation of service performance on the fixed route system and the development of a service plan to improve the system. Integrated into the planning process, we led three phases of community, including traditional public meetings, pop-up events, focus groups, stakeholder meetings, and online engagement strategies. Our team combined our analysis of quantitative and qualitative data to develop a service plan that will address the community’s transit needs, and includes both fixed route and flexible transit service. In addition to transit service planning, the TDP included development and implementation of a prioritization methodology, ridership forecasting, and a financially constrained implementation plan.