This thesis sought to validate the Self Concept Questionnaire (SCQ) created by Stipek and colleagues (1990) and investigate the previously documented relationships between mirror self-recognition and social and cognitive factors with that of the SCQ, a broader measurement of self-awareness. The overarching aim was to identify the developmental antecedents and consequents of self-awareness. Chapter 1 offers a comprehensive review of what it currently known about the development of self-awareness, highlighting the methodological and theoretical emphasis on mirror self-recognition. In the first study (chapter 2) we validated the SCQ for 199 participants aged between 14 and 54 months using exploratory and confirmatory factor analysis. The original four factor loading was replicated but resulted in a modified version with a question regarding the mirror mark test omitted due to low factor loading. The development of the four factors of SCQ followed a similar trajectory as reported by Stipek et al. (1990) with autonomy developing at approximately 14 to 17 months, self-recognition at 18 to 21 months, and self-description/ self-evaluation and emotional response to wrongdoing at approximately 26 to 30 months. This trajectory was replicated longitudinally in a reduced sample of 74 participants, providing the first longitudinal confirmation of Stipek et al.’s (1990) model. However, unlike Stipek et al (1990) we did not find a clear ontogenetic distinction between cognitive and emotional selfevaluation. In study two (chapter three), utilizing data from the same 199 participants in our cross-sectional study, including the SCQ and a variety of additional established questionnaires and demographic questions we found that alongside age, both cognitive (pretend play, imitation, self-regulation and compliance, and general cognitive development) and social factors (attachment and prosociality) could be used as equally strong concurrent predictors of self-awareness accounting for 57% and 60% of the variance in SCQ scores respectively. Importantly, when both cognitive and social factors were brought together, age, pretend play, prosociality and attachment all emerged as significant predictors of selfawareness, accounting for 63.9% of the variance. This confirms that, accounting for shared variance, the development of self-awareness is related to both social and cognitive development. Finally, in study three (chapter 4), we explored the antecedents and consequents of self-awareness by considering predictive longitudinal relationships across a three month period for 74 children aged between 17 and 37 months. Age and pretend play emerged as the strongest concurrent predictors of SCQ performance at three month follow up for the reduced sample. However, pretend play was not longitudinally related to SCQ scores implying that the two developments are not causally related. Further, although age, imitation and prosociality at time one were related to SCQ scores at time two, baseline SCQ performance was ultimately the best predictor. Thus, the developmental antecedents of selfawareness remain an open question. However, SCQ performance was a strong developmental predictor of prosociality at time two, even when accounting for baseline prosociality scores. This result suggests that the increase in prosociality witnessed across 2 to 3 years might be partially explained as a consequence of the development of self-awareness, where cognitive and emotional self-evaluation supports the development of the moral self. In Chapter 5 we take stock of these findings, summarizing the key contributions of the thesis and setting them in theoretical and methodological context; including reflection on limitations and key areas for future enquiry.