This article reviews empirical evidence to show that two concepts- attention and intelligence-are related at the empirical level. Data are presented to demonstrate that intelligence correlates with different types of attention, including sustained attention, search, attention switching, and vigilance. The most significant findings reported here derive from work on divided attention (dual or competing tasks) in which two markers for primary factors were given simultaneously on different channels. Under these conditions, the correlation between the components increases, relative to the single-task condition, implying an increase in the general factor loading. The theoretical implications of this finding are discussed in terms of attentional resources and working memory. Finally, these results are considered in relation to theories of the structure of abilities and particularly in relation to the theory of fluid and crystallized intelligence.