This report summarizes four approaches proposed by transportation consultants on how transportation planning models should and could be improved. New approaches can meet new forecasting requirements, address the impacts of new transportation technology, and exploit the travel behavior theory and methodology that has developed over the past two decades. This document identifies common themes in the approaches and elements missing from some approaches, with the aim of developing a research plan for future models. Topics highlighted include microsimulation approaches to travel demand forecasting, dynamic assignment models, use of geographic information systems (GIS) as a platform for forecasting models, and linkages between travel demand and mobile emissions models.