The focus of this issue of MRS Bulletin is to explore the impact of materials science and technology on microelectronics packaging and integration. Progress in microelectronics packaging has been intimately tied to the continuous advances made in the associated materials, process technologies, and design tools. This is especially true now, as packaging moves into an era driven by the need for complex system-level solutions. This issue is our attempt to present the current status of microelectronics packaging technology and integration and to highlight various perspectives on the future evolution of the field.