Algorithm Engineering and Experiments (ALENEX12) will be held on January 16, 2012, at The Westin Miyako, Kyoto, Japan. The aim of ALENEX is to provide a forum for presentation of original research in the implementation and experimental evaluation of algorithms and data structures. We invite submissions that present significant case studies in experimental analysis or in the implementation, testing, and evaluation of algorithms for realistic environments and scenarios, including specific applied areas that present unique challenges in their underlying algorithmic problems. Experimental analyses may tighten, extend, or otherwise improve current theoretical results. Some possible areas of applied algorithmic research, for example, are from databases, networks, operations research, computational biology and physics, computational geometry, and the world wide web. Submissions are encouraged that address algorithms and data structures for multicore computing, distributed memory, high performance computing, and other areas of parallel and distributed processing. We also invite submissions that address methodological issues and standards in the context of empirical research on algorithms and data structures.