One of the biggest open questions in the study of relativistic nuclear collisions is the proper interpretation of collectivity (i.e., fluid-like behavior) in small collision systems. The discussion has frequently centered on observables such as anisotropic flow, strangeness and/or heavy flavor abundances, and jet quenching signals (or lack thereof). In this talk, I consider the implications of collectivity for a class of observables derived from intensity interferometry which probe the size and shape of the particle production process in nuclear collisions. In particular, I will discuss some recent work on the geometry of small systems which evolve hydrodynamically. I will also describe some similar, ongoing efforts to apply intensity interferometry to non-hydrodynamic models, in the hopes that this will bring additional clarity to the discussion surrounding the correct interpretation of collective signatures.
