Understanding and preventing high school failure is a national priority. Structural strain and general deviance theories attempt to explain late high school failure. The authors tested the hypotheses that general (vs. specific) deviance and academic competence mediate the relationships between structural strain factors (gender, ethnicity, and socioeconomic status [SES]) and 12th-grade high school failure. Independent variables of structural strain and mediational variables of drug use, sexual involvement, school trouble, delinquency, and academic performance were assessed in a sample of 754 8th graders and used to predict 12th-grade high school dropout and number of missed months of school (reflecting a latent construct of High School Failure) in the 12th grade. High school failure was directly predicted by earlier General Deviance, poor Academic Competence, low Family SES, and tobacco use. All ethnic and gender differences in high school failure were mediated by deviance and academic ability or accounted for by Family SES discrepancies.