The concept of the pollen zone as a fossil assemblage zone is discussed, and the advantages of numerical approaches to the recognition and delimitation of such zones are considered. Existing procedures are reviewed, and original constrained agglomerative and divisive procedures are advanced. The results of these procedures are discussed in relation to existing zonation schemes for three sets of data, and the limitations and potentialities of the procedures are considered. The initial zonations suggested by visual inspection are, in general, confirmed by the numerical procedures. The application of these procedures to the subdivision of both pollen and macro-fossil data in the same stratigraphical sequence is also discussed. Details are given of the computer time and storage required for the analyses.