Three studies tested the relationship between political extremism and cognitive complexity in an adult sample (N = 135), a sample of students (N = 145), and a sample of political party members (N = 47). According to value pluralism theory, advocates of extreme ideologies exhibit low levels of cognitive complexity. Context theory, in contrast, states that extremists think in a more complex and sophisticated way about politics. In accordance with context theory, significant positive correlations between cognitive complexity and extremist ideology were found in all samples. The results of these studies also revealed weak correlations among the cognitive complexity instruments used in previous research. Problems concerning the measurement of cognitive style and cognitive complexity are discussed.