Multijunction solar cells based on III-V semiconductors are the most efficient solar cells in the world, with record efficiencies of over 40%. These devices offer the promise of very competitive solar power systems exploiting the high efficiency devices under high optical concentration. To make this promise a reality, Spectrolab is conducting a multi-year program to develop solar cells with still higher efficiency and substantial cost reductions and to fully characterize and qualify them for reliable performance in the field. Qualification of a second generation cell technology has recently been completed. Cell performance, qualification, and field test data will be presented; progress on performance improvements, cost reductions, and manufacturing capacity plans will be discussed. Development of these high-performance multijunction CPV cells promises to break the bottleneck currently limiting growth in photovoltaic power generation.