Two current theoretical frameworks inform this thesis: General Strain Theory and the life-course perspective. Data from Canada's NLSCY was used to test General Strain Theory during two stages of the life course. Twelve hypotheses were created. Descriptive statistics were used to test the first four hypotheses and two regression models were created to test the subsequent hypotheses. The first model tested whether strain would lead to childhood and adolescent aggression. The second model tested whether support would weaken the effects of strain on aggression. The results indicated that strain leads to pre-adolescent and adolescent aggression. Parental support was found to weaken the effects of both strains on adolescent aggression. Parental support was shown to weaken the effect of school strain on pre-adolescent aggression but was not shown to weaken the effect of parental strain on pre-adolescent aggression. The implications of these findings are discussed along with suggestions for future research.