Feed influences directly growth and survival in land snails. Here, we investigate the influence of diet and isolation on growth and survival in Bulimulus tenuissimus (d'Orbigny, 1835) in the laboratory. Animals were maintained individually and in groups and three different types of diets: lettuce, ration and both lettuce and ration (mixed diet) for 210 days. Isolated animals, in all diet types, grew more rapidly than grouped animals. Also, snails fed with lettuce grew most slowly in isolated or grouped treatments. Within isolated or grouped treatments, growth rates were similar for the ration and the mixed diet. Mortality rate was higher in animals fed on lettuce only, in both density treatments. Thus, diet and density are important components of the population dynamics of B. tenuissimus.