The aims of this study are twofold: to propose methods for measuring (dis)similarities in the organization of valency class systems across languages, and to test them on a sample of European languages in order to reveal areal and genetic patterns. The data were gathered for 29 languages using a questionnaire containing 130 contextualized uses of bivalent predicates. The properties under study include (i) lexical range of transitives, (ii) lexical range of valency frames defined in terms of the “locus” of non-transitivity (whether A or P arguments are encoded by oblique devices), (iii) overall complexity of valency class systems, and (iv) lexical distribution of verbs among valency classes. In case of the simpler properties (i)–(iii), maps with quantified isoglosses and pairwise comparison of languages based on Hamming distance are used. For (iv) these methods are inapplicable (valency classes cannot be equated across languages), and I propose a distance metric based on entropy and pairwise mutual information between distributions. The distance matrices are analyzed using the NeighborNet algorithm as implemented in SplitsTree. I argue that more holistic properties of valency class systems are indicative of large areal effects: e.g., many western European languages (Germanic, Romance, Basque and some Balkan languages) are lexically “most transitive” in Europe. Low-level areal signal is clearly discernible in the data on more subtle aspects of the organization of valency classes. The findings imply that distributions of verbs into valency classes can develop quickly and are transferable in contact situations, despite drastic dissimilarities in argument-coding devices.