Friendship in childhood promotes cognitive development, subjective well-being, and social support. Nevertheless, gaps in the empirical and theoretical investigations posit the need for further studies. This paper aims at reviewing recurrent conceptual perspectives and empirical studies used in research on children's friendships. It also reviews research conducted with Brazilian children. It discusses friendship in children with Attention Deficit/ Hyperactivity Disorder (ADHD) based on Brazilian and international studies. Finally, those studies are critically analyzed and future research endeavors on friendship in children with and without ADHD in the country are suggested. Key words: friendship, development, disorder.