The 2012 GRC on Crystal Engineering follows the highly successful first ever GRC on Crystal Engineering (2010) which had over 160 international participants. The 2012 Crystal Engineering GRC will also include a new and exciting Gordon Research Seminar (GRS) in which only students and postdocs may present or lead discussions. Both the GRC and GRS on Crystal Engineering provide a forum for the discussion of the current state of the art of this rapidly evolving, highly interdisciplinary field, to identify and debate open questions, and to point out new and promising research directions. Crystal engineering is the design and synthesis of functional solid-state structures (e.g., new organic molecular crystals and metal-organic co-ordination polymers and framework solids (MOFs)), based on a bottom-up approach from smaller building blocks such as neutral organic molecules, and organic or inorganic ions. Typical design strategies use hydrogen bonds and coordination bonds, which define sub-structural units that are called respectively, supramolecular synthons and secondary building units. This subject cuts across the traditional divisions of organic, inorganic, and physical chemistry, making for a very eclectic blend of ideas, techniques, and strategies. This GRC and the accompanying GRS will provide a forum for the discussion of the current state of the art of this rapidly evolving, highly interdisciplinary field, will identify and debate open questions, and will point out new promising research directions. These conferences will bring together experts with a diverse background and will consist of the following sessions: * Nanocrystals * Nucleation, Crystal Growth, and Solid State Reactivity * Polymorphism and Crystal Structure Prediction * Magnetism and Conductivity * Catalysis in Porous Materials * Design, Synthesis, and Properties of Co-crystals * Industrial Applications of Crystal Engineering * Coordination Polymers * Halogen Halogen and Other Weak Interactions