Some aspects of vegetation structure in two chalk grasslands were studied throughout the year in relation to the occurrence of some short-lived plant species per life-cycle stage. Whereas the main growth period is in May June, there is another relatively important growth period in less productive stands in August. When the species are arranged in the order of their tolerance for less to more productive micro-sites during the adult life phase the following sequence emerges considering a generally weak significance in the results. Carlina vulgaris, Euphrasia officinalis, Gentianella germanica, and Scabiosa columbaria, Linum catharticum, Anthyllis vulneraria, and Daucus carota. In some species this preference was found to shift from seedling to vegetative and reproductive phase. Each life phase usually has its special abundance with regard to vegetation density. * Nomenclature follows Heukels & van Ooststroom (1970) ** The authors are very grateful to Prof. Dr. J. J. Barkman and Prof. Dr. R. Brouwer for their inspiring help and interest. They are greatly indebted to Dr. H. J. During and Dr. J. H. Willems for their continuous support and for their useful comments on this paper. They like to thank Mr. T. Schipper for preparing the figures and Miss S. M. McNab for making some linguistic improvements. Vegetatio 52, 91-102 (1983).