||Visibly distinct microstructural patterns during phase transformations have long caught the eye of researchers, beginning with the first light optical microscope micrographs of pearlitic lamellae and cast iron dendrites in the late 1800s. This symposium will explore the fundamentals of length scale selection in all materials, including the related question of how cooperative growth of multiphase transformation products is established. The breakdown of such patterns upon prolonged annealing, increases in driving force, etc. is also of interest. The scope includes experimental, theoretical, and modeling studies of how particular length scales are established in relation to thermodynamics, kinetics, morphology, crystallography, and interfacial structure. Solidification topics include dendritic, cellular, and lamellar/rod growth. Solid-solid transformations of interest include: pearlite, discontinuous precipitation and coarsening, and interphase boundary precipitation. In-situ and in-field studies are welcome, as are those of phase transformations resulting patterned microstructures that are in some way irregular or abnormal.