Two studies used latent growth-curve analysis to examine the relation between witnessing violence and changes in problem behaviors (drug use, aggression, and delinquency) and attitudes during early adolescence. In Study 1, six waves of data covering 6th to 8th grades were collected from 731 students in urban schools serving mostly African-American students. Strong cross-sectional relations were found between witnessing violence and other variables. Witnessing violence also predicted subsequent increases in drug use and attitudes supporting violence and decreases in value on achievement. In Study 2, five waves of data covering 6th to 9th grades were collected from an ethnically diverse sample of 922 students at four rural schools. Witnessing violence predicted subsequent changes in drug use, but not in other variables. Growth-curve trajectories indicated that boys reported greater increases in witnessing violence than girls. Strong cross-sectional relations again were found between witnessing violence and other variables. Increases in witnessing violence also were related strongly to increases in problem behaviors and attitudes supporting violence and to decreases in attitudes supporting nonviolence. These findings have important implications for research and intervention efforts. (Contains 1 table, 3 figures and 2 footnotes.)