Executive Summary: Over the past decade@ the use of consultants by state transportation agencies has increased significantly. In recognition@ AASHTO has seen a need to conduct a study@ to develop this guide that discusses findings and presents methods@ procedures@ and suggested recommendations for making the most effective use of consultants. Agencies are continuing to be faced with dynamic programs which seem to have larger peaks and valleys. They are also facing significant changes in how business is to be conducted. In addition@ staffing limitations@ hiring freezes and other constraints are adding pressures to the expectations to deliver quality projects on time and within budget. Consultants have become a key resource and extension of an agency's professional workforce to deal with these dynamics and deliver the program. While not always less costly@ the use of consultants to balance workforce with workload can be cost effective. This guide is intended to be a reference for agencies to use in further developing their consultant program@ organizing and training their staffs@ selecting consultants@ developing consultant contracts@ and managing their consultant program and workforce. The primary objective of AASHTO and this task force was to provide a guide to assist transportation agencies.