In many cases network analysis problems can be defined (abstracted) in terms that do not require a GIS for data manipulation, solution or presentation. For this reason algorithms for their exact or approximate solution are available as stand-alone code modules or as libraries providing solutions for generic problems, which then may be integrated into application suites with final output in map, list and/or table form. For example, problems involving the optimal selection of one or more locations in the plane (e.g. depots) given a set of point locations representing demand (e.g. customer sites) simply may require the relevant coordinate set (and associated demand levels) as input. The same observation applies to problems where a route traversing a set of points is required, but for which no explicit prior network has been defined. Likewise, assuming that a predefined network exists, many problems can be solved without detailed knowledge of the shape of links between network nodes — in general only their length or a related measure such as travel time in each direction is required, often provided as a shortest path or least-cost matrix. In this chapter, therefore, we discuss the solution to a range of network optimization problems using both GIS and non-GIS toolsets. Recommended reading to accompany this chapter includes: Tinkler (CATMOG 14), Scott (1971), Miller and Shaw (2001) “Geographic Information Systems for Transportation”; Ahuja et al. (1993) “Network flows: Theory, algorithms and applications”; Rodrigue et al. (2006) "The geography of transport systems"; and Daskin (1995) “Network and discrete location: Models, algorithms and applications”.