The 12th USENIX Symposium on Networked Systems Design and Implementation provides a high-quality, single-track forum for presenting results and discussing ideas that further the knowledge and understanding of the networked systems community as a whole, continue a significant research dialog, or push the architectural boundaries of network services. This year's program includes 42 refereed paper presentations on data centers, software-defined networking, wireless, data analytics, protocol design and implementation, virtualization, and much more. Six of these papers will be presented as part of the operational track and describe the design, implementation, analysis, and experience with large-scale, operational systems and networks. Register by April 13 and save. Additional discounts are available! www.usenix.org/nsdi15/lj