Equivariant cohomology theories are cohomology theories incorporate a group action on spaces. These types of cohomology theories are increasingly important in algebraic topology but can be difficult to understand or construct. In recent work, Angelica Osorno and I have developed a construction for building them out of purely algebraic data by controlling pieces with different isotropy types under the group action. Our method is philosophically similar to classical work of Segal on building nonequivariant cohomology theories.