Broadly defined, the field of mesoscale science connects the microscopic and macroscopic worlds. The differences in sizes, arrangements, complexity, and operating principles between microscopic objects (atoms and molecules) and macroscopic assemblies (chemically and structurally complex bulk materials) are enormous. However, these entities are linked and connected by a series of intermediate — or "mesoscale" — architectures and phenomena that can be experimentally probed and observed, theoretically understood, and ultimately physically controlled, manipulated, and tailored. Mesoscale science encompasses the observation, understanding, and control of these intermediate-scale architectures and phenomena.
The systematic investigations of mesoscale architectures and phenomena — ubiquitous as the hierarchical "staircase" connecting atoms to bulk materials — are somewhat in their infancy, but offer unprecedented opportunities. Because of the ever-accelerating advances in modern experimental, theoretical, and computational capabilities, the opportunities afforded by mesoscale science can now be seized – and the benefits resulting from controlling and mastering mesoscale architectures can be fully exploited to create and optimize new functionality.
A set emerging basic research needs in the field of mesoscale science has been identified and documented in a recent report of the DOE Office of Basic Energy Sciences (BES) Advisory Committee (BESAC) entitled "From Quanta to the Continuum: Opportunities for Mesoscale Science", and available on the BES web site . This report broadly outlines the status of knowledge in the field, the challenges and opportunities, and the benefits of mastering mesoscale science phenomena.
 BESAC report "From Quanta to the Continuum: Opportunities for Mesoscale Science" .