The motion of a cell is modelled by a continuous-time Markov chain whose states are sectors of angles at which the cell moves, plus an additional ‘ 0 ’ state, where two or more cells adhere to each other. The stationary distribution for this Markov chain is readily computed, and the componentp¯(0), the probability that a cell will ultimately end up adhering to another is used as a measure of cell adhesion for the cell type under consideration. The Markov chain model also permits the definition of a measure for contact alignment and the formulation of a mathematical definition for ‘ sorting out ’ of different cell types.