A review of factors governing vegetation change in heathlands and grasslands is presented, with emphasis on soil factors. Climate, microclimate, fire, fauna, grazing by vertebrates, grazing by invertebrates, disease, dispersal, establishment, competition, allelopathy, stabilization, soil formation and podzolizati0n are discussed with emphasis on inconsistencies and lacks in our present knowledge. Examples are mainly from NW European Calluna heath and related woodlands.