The present paper explores how "written emotional disclosure", in particular writing about personal feelings and thoughts concerning discriminatory events, can represent an important opportunity for children to engage in the transformation of categorical boundaries through complex cognitive and emotional processes. In particular, the paper explores from a comparative perspective: 1) how minority and migrant children express their opinions about personal and vicarious experiences of discrimination in different cultural and social contexts; 2) how, through these writings, children develop some cognitive and emotional coping strategies to handle external categorization. At the educational level, children's expressive writings can represent relevant material for educators in order to understand meanings that pupils bring with them into their classroom, as well as educational tools for children in multicultural contexts. I draw on some extracts from open-ended essays written by minority and migrant children aged 9-10 attending elementary schools in Japan and in Italy.