[2] His work focuses on the theory of soft matter, such as polymers, colloids, gels, liquid crystals, and granular material.

He has worked on theories of active matter, particularly dense suspensions of self-propelled particles which can include motile bacteria.

At Edinburgh, Cates was the Principal Investigator of an EPSRC Programme Grant, awarded in 2011, entitled Design Principles for New Soft Materials.

He has served as an elected member of the Council of the Royal Society, and chairs the International Scientific Committee of ESPCI ParisTech.

He was also elected a member of the National Academy of Engineering in 2019 for research on the rheology, dynamics, and thermodynamics of complex fluids, and for scientific leadership in the European Community.