This article explores the evolution of Tri-Met, the mass transit agency serving Portland, Oregon, and its contractual relationship, begun in May 1989, with the Portland Police Bureau (PPB) to provide police service to that transit agency. At the time of the contract, the PPB had no prior experience in providing direct service to any agency such as Tri-Met. Tri-Met services three Oregon counties, has limited service into a neighboring Washington State county, and is divided into bus and rail components covering 770 bus-route miles. The unit's struggle to carry out its mission to provide safe transport for system users has resulted in several useful ideas that are discussed in this article. Efforts to address threats by gangs, to provide platform security for the Metro Area Express and shelter security at bus stops, as well as efforts to increase vehicle parking security are noted.