Dr. Horn's research interests relate to how social-cognitive development and social institutions influence the ways in which adolescents reason about peer harassment, peer discrimination, and peer relationships (in particular, harassment based on peer group membership, sexual orientation, and gender identity/expression). Additionally, she is interested in factors (e.g., age, religion, school context, intergroup context) related to sexual prejudice among adolescents and adults.

In her research, she is interested in how normative changes in adolescent social concepts affect the ways in which adolescents negotiate tensions between their moral understandings of how best to treat others with their conceptions of what is conventionally required for group membership and social solidarity. These conventional expectations are interwoven with adolescents' construction of personal identity, and intimately connected with their assumptions about personhood, and psychological normality. 

Dr. Horn is especially interested in how adolescents' concepts of person characteristics as essential or innate rather than personally chosen or constructed factor into the complex of decisions that result in acceptance of social exclusion and peer harassment, as well as how features of the social context relate to adolescents social reasoning about these issues.

In her teaching, she is interested in adolescent development, broadly, and how psychological, social, and cultural factors impact this development. She also examines how to use our knowledge about adolescent development in creating educational and social context that support and promote positive developmental outcomes for all youth, and specifically for youth who identify as lesbian, gay, bisexual, or transgender.

My interest and experience in applied clinical-community research has solidified my focus on considering contextual and cultural factors when working with children and families. As a result, my research seeks to develop an integrated approach to studying African-American children's normative development and utilizing this basic research to create culturally and developmentally appropriate behavior promotion programs.

Specifically, I examine young African-American children's emotional and social competence, including children's affective responses to sociomoral events, and the ways in which schools can support children's development in this area. The findings from this research will lead to the creation a school-based promotion program targeting urban-dwelling African-American children's social and emotional competence.