Vitamin A (retinol) is a necessary nutrient for vision, reproduction, growth, and immune function. Pro-vitamin A carotenoids are an important source, especially in developing countries. While preformed vitamin A is readily available from foods, carotenoids are much more difficult to assimilate. A number of factors have been identified that either enhance or hinder the bioavailability of carotenoids. These have been presented in the literature and given the mnemonic SLAMENGHI by some researchers. The following factors are summarized: Species of carotenoid, molecular Linkage, Amount in the meal, Matrix Properties, Effectors, Nutrient status, Genetics, Host specificity, and Interactions between factors. Identifying which of these are key issues for the general public, and promoting the increased consumption of fruits and vegetables with moderate and high levels of pro-vitamin A carotenoids, are important to vitamin A status and overall good health.