Religious fundamentalism is conceived as a distinctive set of beliefs and attitudes toward one's religion, including obedience to religious norms, belief in the universality and immutability of its principles, the validity of its claims, and its indispensability for human happiness. Surveys of Egyptian and Saudi youth, ages 18-25, reveal that respondents with higher levels of fundamentalism are more likely to rely on religious authorities as the source of knowledge about the sociopolitical role of Islam, support religious law, be fatalistic, and feel insecure. They are also less likely to watch TV. Saudi females are more fundamentalist than males, but in Egypt, the opposite held true. Country-specific effects are present, and there are implications for future research. (Contains 4 tables and 10 notes.)