The current study seeks to replicate and extend the research on the effects of implicit theories of intelligence. Study 1 tested the hypothesis that an incremental theory- a belief that intelligence is malleable would result in mastery-oriented behaviour when faced with setbacks and an entity theory- a belief that intelligence is fixed would result in helpless achievement behaviour when faced with setbacks. Study 2 testes the hypothesis that test scores would change when faced with setbacks relative to the entity or incremental condition. Study 3 investigates whether implicit theories of intelligence can predict grade average and self-esteem. Study 1 revealed that incremental theorists were not more likely than entity theorists to attribute setbacks to effort. Furthermore, it also revealed that incremental theorists were not more likely to take remedial action when faced with setbacks. Study 2 found no significant differences in test scores in the incremental and entity condition after the setback. The findings of Study 1 and 2 contradicts the research of Hong et al (1999) by finding no significant differences in task choice or attributions across incremental or entity conditions. Study 3 found that implicit theory did not significantly predict grade average or self-esteem. These finding will discussed in turn in relation to its effects on the implicit theory model.