The scientific and technological progress in inertial confinement fusion has been substantial during the past decade. However, many of the technologies needed for an integrated inertial fusion energy system are still at an early stage of technological maturity. For all approaches to inertial fusion energy there remain critical scientific and engineering challenges. In this interim report of the study An Assessment of the Prospects for Inertial Fusion Energy, the Committee on the Prospects for Inertial Confinement Fusion Energy Systems outlines their preliminary conclusions and recommendations of the feasibility of inertial fusion energy. The committee also describes its anticipated next steps as it prepares its final report. Table of Contents Front Matter Interim Report Appendix A: The Basic Science of Inertial Fusion Energy Appendix B: Statements of Task Appendix C: Panel Membership and Staff for the Panel on the Assessment of Inertial Confinement Fusion (ICF) Targets Appendix D: Agendas from Committee Meetings and Site Visits Appendix E: Bibliography of Previous Inertial Confinement Fusion Studies Consulted by the Committee Appendix F: Agendas from Meetings of the Panel on the Assessment of Inertial Confinement Fusion (ICF) Targets Appendix G: Glossary of Terms and Acronyms Used in This Report