City managers play an influential role in brokering intergovernmental service arrangements on behalf of their jurisdiction, yet their motivations for doing so are not well understood. One argument, drawn from theories of bureaucratic entrepreneurship and ambition theory, suggests that cities with managers who are motivated to advance their careers will parlay more interlocal service delivery as means of capturing economic efficiencies. Such strategies serve to build their personal resumes of career achievements. An alternative argument suggests more altruistic motives, including a desire for increased social equity and valuing the common good of the region, compel city managers to pursue interlocal service arrangements. These competing theories are tested on 134 large municipalities, using survey data from the city managers of these jurisdictions, coupled with interlocal revenue and expenditure data for these cities. Results yield greater support for the first theory. However, progressive ambition possesses complex consequences for interlocal service delivery choices. Jurisdictions managed by city managers with career-enhancement ambitions are more likely to sell services to other local governments. Yet, they are significantly less inclined to buy services from other jurisdictions, thereby underscoring entrepreneurship in shaping managers’ professional trajectories.