Most people support the idea that we live in a complex society and that complex evaluations and strategies are needed in order to effectively address most societal problems. However, little attention is generally paid to the degree of presence of complex thinking in youths' attitudes towards the most significant issues that characterize contemporary human societies. This paper presents a preliminary analysis of the relationship between youths' "complex thinking" and their evaluations of and attitudes towards one of these issues, namely cultural diversity. It examines some excerpts from anonymous open-ended essays on "multiculturalism" in Italy, recently written by pupils aged 14-18. The paper indicates that youths' low levels of complex thinking are often expressed through a prejudiced and basically negative representation of a multicultural society, and through a scarce awareness and a simplistic description of their personal and others' emotions related to this representation. It also indicates that high levels of complex thinking usually characterize youths' positive relationship with and thoughtful understanding of cultural diversity. The paper underlines the importance of fostering the development of high levels of complex thinking at the educational level, so as to strengthen youths' capability of building a more autonomous and complex outlook on their relationship with cultural diversity, and with diversity in general.