The underlying mechanisms of suggestibility consist both cognitive and social components. Generally speaking, age is associated with decreased suggestibility when the suggestibility is examined from the cognitive perspective. The dissertation examines how the acquisition of metacognitive ability (metamemory, narrative knowledge, source monitoring, and knowledge about knowledge) influences the extent of suggestibility from both cognitive and social perspectives. Preschool children's suggestibility was measured with Video Suggestibility Scale for Children (VSSC) (Scullin & Ceci, 2001), which consists of two subscales, Yield focusing more on the cognitive aspect of suggestibility and Shift focusing more on the social aspect. Older children recalled more information, yielded to fewer misleading questions and shifted more answers upon repeated interview following negative feedback. In Study 1, both aspects of metamemory (declarative and procedural) were involved. Children who could better monitor their memory performance in the procedural metamemory task were less likely to yield to misleading questioning. In contrast, children with better declarative metamemory changed their answers more. Study 2 investigated the relation between preschoolers' suggestibility and their knowledge about narrative context, which refers to children's ability to appreciate the accuracy demand of the narrative context and take audience's perspective into account. Children's knowledge about narrative context appeared to be an independent predictor of the tendency to shift their answers in repeated interviews following negative feedback. The purpose of Study 3 was to examine the relation between source monitoring and suggestibility. On one hand, children who could better monitor sources of information were less likely to yield to misleading questioning. On the other hand, children with better source monitoring ability changed their answers more. Study 4 examined the relation between children's knowledge about knowledge and suggestibility. An interview examining two types of knowledge about knowledge (temporary, situational judgement and trait, individual-dependent judgment) was specially designed for the study. There was no overall relation revealed but some individual items were associated with the extent of suggestibility. Taken together, the findings from the four experiments indicate the relation between metacognitive abilities and suggestibility in preschool children is complex. These studies extend our understanding of the individual factors associated with suggestibility, from both cognitive and social aspects.