This thesis aims to retrofit existing infrastructure and future development plans for a south Fargo neighborhood in order to transform the neighborhood into a walkable mixed-use urban center. Walkability is defined by providing a diverse mix of destinations within a five to ten minute walk along well maintained transportation corridors. A mixed-use urban center enhances walkability by providing a culturally significant neighborhood that locates residential, retail, commercial, and open spaces within close proximity of one another. The research examines smart growth urban planning principles along with implemented urban center designs from around the nation, focusing on the integration of building usages and placements, street networks, and open spaces. The research is then applied to design a retrofit plan for the 320 acre Urban Plains neighborhood in south Fargo.