Abstract The kinetics of colicin adsorption are worked out on the assumption that each bacterial cell has s specific sensitive receptors (0 ≤ s ≤ ∞), and that a cell remains viable as long as no more than r (0 ≤ r ≤ s) of these receptors are occupied (hit) by colicin. Six Special Cases of this generalization are defined with suggested nomenclature. The behaviour of the Special Cases is examined under 3 model systems: (a) Homogeneous Model (all cells in a population have the same number of receptors); (b) Distributed Receptor Model (the number of receptors per cell is not constant within a specified population); (c) Heterogeneous Model (each cell of a population is sensitive to ? (or more) sorts of colicin, both of which are present in its environment). The likelihood is discussed that an experimentally obtained survivor plot would lead to an unequivocal choice of one (or none) of these models as a basis for interpretation, and the determination of the necessary parameters is discussed in appendices.