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.