Intervention tricals can principally be classified into community or clinically oriented designs. The clinical approach of the randomized controlled trial (RCT) implies the individual randomization of a volunteer population into a study and a control group. In community-oriented trials, however, the study and control group are not composed of individuals, but rather of total population groups (e.g. communities, factories). The paper gives first an overview over the historial development of epidemiological methods as the basis for both study types. Shortcomings and advantages both of RCT's and of community trials are discussed, using the examples of the "diet-heart" hypothesis and of the National Research Program 1A design, respectively. The two study types uses as primary endpoints for the analysis changes in risk factor distribution, morbidity and/or mortality. A recent alternative is presented, too: advances in angiography allow direct measurements of changes in vessels with atherosclerotic disease. The different study types available complement one another in trying to understand the mechanisms involved in disease of multifactorial origin.