A clear understanding of human population growth, consumption patterns, and their effects on the environment, particularly amongst our future leaders, is essential for proper allocation of conservation efforts. We report on the results of a written questionnaire assessing the knowledge and attitudes of undergraduate university students majoring in a range of disciplines in the United States of America (USA) and in Costa Rica (CR) regarding population- and environment-related issues. Our results indicated limited knowledge about human population growth and the environment, with USA students and male students more often responding correctly to factual questions on demography and global environmental change than CR students, who nonetheless were generally more pessimistic about environmental quality and the carrying capacity of the planet. USA students, however, more often recognized the link between human population size and environmental quality. Education on population and environmental issues will be improved if: (1) linkages between population size, consumption, and environmental quality are taught; (2) the effects of individual actions on environmental quality are emphasized; and (3) environmental education is tailored to local issues.