Our laboratory has f cancer prevention using freeze-dried berries, mainly black raspberries, for more than two decades. Berries contain many known agents with chemopreventive potential including certain vitamins, minerals, simple and complex polyphenols, phytosterols, and various fiber constituents. Because berries are approximately 80-90 % water, the freeze-drying process concentrates these bioactive constituents approximately tenfold. This chapter describes methods we use to harvest the berries, grind them into a powder, and determine the nutrient, chemical, and microbial content of the powder before use in both preclinical and clinical studies. We have found that berry powder, when added at 5.0-10 % of the diet, protects against chemically induced cancer in the rodent esophagus and colon, and other laboratories have demonstrated protective effects in the rodent oral cavity, mammary gland, and skin. Bio-fractionation studies indicate that the anthocyanins in black raspberries are important for their chemopreventive effects. The berries function to reduce cell proliferation, inflammation, and angiogenesis and to stimulate apoptosis and differentiation, and they influence the expression levels of multiple genes and signaling pathways associated with these cellular functions. Black raspberry and strawberry powders are well tolerated by humans for at least 6-9 months when consumed orally at doses as high as 60 g/day. As an example of their effects in humans, we describe here the ability of black raspberries and strawberries (STRW) to modulate the development of premalignant lesions (Barrett's esophagus and esophageal dysplasia) in the esophagus. We hope that the information and methods in this review will be helpful to others who are considering the use of food-based approaches to cancer prevention.