This study surveyed the self-expressed worries of 3,983 adolescents in Northern Ireland, with a specific focus on identifying age and gender differences. Students aged thirteen to eighteen years completed a 138-item scale in which they indicated frequency of worry across a range of social and personal issues. Analysis of their responses revealed that females reported worrying significantly more frequently than did males, particularly in regard to transition from school and personal and academic issues. Students over sixteen years old reported worrying significantly less frequently than did their younger counterparts. These results are discussed in the context of societal, gender-related, and developmental influences.