Joanne Cohn is a theoretical cosmologist working on large scale structure and galaxy formation, using analytic methods, simulations and observational data. A large part of her recent work has been on comparing models to each other and to observations. These studies range from validating mock catalogues for large observational galaxy surveys such as DES and LSST to using machine learning to compare full sets of galaxy histories produced by different detailed numerical simulations. In structure formation, she has been using analytic methods to characterize the cosmic web and its evolution, and to characterize specific phenomena such as baryon acoustic oscillations. Her main focus is on finding and testing simplified models for trends which arise within galaxy and structure formation. Her earlier related work includes studies of galaxy clusters (in particular, the effects of the cosmic web on finding them and finding their mass), mergers of galaxies and clusters, reionization, quasars, and gravitational lensing, mostly within the context of simulations or analytic models.