The evidence on cognitive decline in senile dementia is reviewed with respect to the distinction between controlled and automatic processing. It is argued that controlled processing, which requires the attentional resources of the individual, declines in early senile dementia. However, automatic processing, which does not require attentional resources, is well maintained until late in the disorder. Implications of this view are drawn for the development of effective screening instruments which can be used for the early detection of dementia in the general population.