This report has been packaged in six separate volumes so that readers can select those volumes that interest them most. Volume I, Summary of Findings on the Alternative Base Period, summarizes the information presented in Volumes II through VI. Volume II, Impact of the Alternative Base Period on Administrative Costs, contains descriptions of the processes and procedures resulting from implementing ABP and estimates of implementation and administrative costs. Volume III, Impact of the Alternative Base Period on Employers, contains analyses of the effects of ABP on employers and descriptions of reporting formats and mediums used. Volume IV, Impact of the Alternative Base Period on the Trust Fund, contains analysis and simulations of the impact of ABP on the trust fund in five states. The Urban Institute was responsible for the contents of this volume as a subcontractor to Planmatics. Volume V, Demographic Profile of UI Recipients under the Alternative Base Period, contains descriptions and analyses of workers eligible for unemployment insurance in New Jersey and Washington and comparisons with regular UI recipients. Volume VI, Handbook for States Implementing the Alternative Base Period, contains information on lessons learned from states with alternative base periods and provides guidelines on how to design and implement such systems.