CROwd Simulation of Situated individuals represents a modern generation simulation as a (social) scientific tool for understanding crowd behaviour. The CROSS model represents individuals in a crowd as social-cognitive agents that are affected by their social and physical surroundings and produce behaviour and behaviour patterns. Understanding is sought by relating the intra- and inter-individual level levels of behaviour generation with behaviour pattern emergence at group level. The CROSS model advances crowd research by adding a description of behaviour at the cognitive (intra-individual) level as well as the use of simulation experiments to test theory. The CROSS model meets the need of crowd research for a theory that reflects the dynamic interplay between individuals and their environment as well as the need for a method that allows for testing.