The curb on urban street systems is subject to severe user competition. The primary competitors are the static users (parked vehicles) and dyanmic users (vehicular traffic and surface transit). In downtown areas, the pickup and delivery of goods are almost exclusively done at curbside and, thus, goods-movement vehicles must compete with the other curb space users. Standards for the allocation of curb space for pickup and delivery (PUD) vehicles are nonexistent. The purpose of this paper is to present a method for determining curbside spatial requirements for PUD vehicles. The method outlines a process whose solution answers the question, Given a set of conditions, what are the curbside spatial requirements for PUD vehicles that would keep the total costs to society (the relevant portions) to a minimum?" Society" includes vehicular traffic, carriers, shippers, curbside automobile parkers, surface transit, and the community at large. This paper presents the components of each societal group that would be affected by varied spatial allocations at curbside and outlines the method for searching out the least cost solution. In addition to the method presentation, a case study is put forward to show that application of the least cost principle does infact give results that are practical and implementable on urban street systems./Author/