Our research studies on cross-cultural relations are to be considered within a theoretical framework whose main core is constituted by a broad definition of diversity. In this context the concept of diversity lies in a continuum ranging, for example, from cultural differences to socio-economic, gender, age, and species differences, up to those differences that in any case are present between two individuals (and even in a same individual in various periods of her/his life), since each individual is "other", whatever her/his cultural, socio-economic, gender, age, species, etc. differences are. Our considerations are also the result of a study we conducted in some Italian schools on 350 pre-adolescents and adolescents' (9-18 years, 176 F and 174 M) attitudes towards multiculturalism. We identified two precise psychological elements at the base of some participants' prejudices: fear, and consequently the perception of a threat, and a lack and/or dearth of knowledge. These elements generally bolster each other. Some specific fears were identified. Another important result of this study relates to the problem regarding whether and, in case, in what degree cultural differences per se negatively affect youths' relationships with peers from different cultures. Our data indicate that many of the difficulties in pupils' relationships with culturally diverse peers at school coincide with or are very similar to the difficulties in their relationships with peers in general, thus supporting the assumption that there are some common basic motivations underlying the acceptance or the refusal of "the other", be "the other" culturally diverse or not. In this study we used "open-ended essays", which were anonymously written by our participants. In the few studies that have been conducted in this field by other researchers the methodology that has been used often limits the free expression of participants' ideas and emotions. What is more, in a few cases it can even condition it in a subtle way. Another significant result of our study is that the contact with diversity, and in particular with cultural diversity, does not necessarily imply fear and the adoption of prejudices. Instead, it can be characterized by curiosity, interest, and empathy.