he International Year of Crystallography has understandably been a celebration of order. From Rene-Just HaÃ¼y's prescient drawings of stacked cubes to the convolutions of membrane proteins, Nature Milestones in Crystallography1 revealed a discipline able to tackle increasingly complex and subtle forms of atomic-scale regularity. But it seems fitting, as the year draws to a close, to recognize that the road ahead is far less tidy. Whether it is the introduction of defects to control semiconductor band structure2, the nanoscale disorder that can improve the performance of thermoelectric materials3, or the creation of nanoscale conduction pathways in graphene4, the future of solid-state materials physics seems increasingly to depend on a delicate balance of crystallinity and its violation. In biology, the notion of 'structure' has always been less congruent with periodicity, but ever since SchrÃ¶dinger's famous 'aperiodic crystal' there has been a recognition that a deeper order may underpin the apparent molecular turmoil of life.