The Pipeline Simulation Interest Group (PSIG) was formed in 1969. Its purpose is to facilitate the interchange of information and to advance the state of the art in modeling, simulation, optimization, steady-state and transient flows, single and multiphase flows, and related subjects as applied to fluid pipeline systems. PSIG is an independent group, and is not affiliated with any other organization. It is administered by an executive council and operates in an unstructured, informal manner. An annual meeting is held each year in spring at various locations around the country. This two and one-half day meeting is attended by about 170 people who represent major gas companies, major oil companies, specialized consultants, and universities in the United States, Canada, Europe, Australia, and Asia. Papers of a high calibre are presented in a relaxed atmosphere where informality is the key. Strong emphasis is placed on discussion of the presented material.