The socio-cognitive functions of infants' pre-linguistic communication, and their later links to language, have been well established through studies on infants' index-finger pointing from 12 months (Carpenter, Nagell & Tomasello, 1998; Liszkowski, 2008). Less is known about the functions of precursory gestures to pointing, such as holdouts and gives. In this thesis I explore the underlying motivations of these earlier gestures, the interplay between infants' gesture use and caregiver input, and the factors that may influence this. In chapter 1, the functions, theoretical approaches and previous research examining infants' pre-linguistic gesture use are considered, with particular emphasis on the social-pragmatic interpretations of these behaviours. This chapter ends with three emerging research questions, and describes three research papers and methods created to answer these. Firstly, what are the underlying motivations behind infants' early holdout gestures? Chapter 2 presents a research paper with an experimental paradigm adapted from the work of Liszkowski and colleagues (2004), which aimed to elicit holdout gestures in 10 month olds, to see if the motive to share attention was present before 12 months. Infants were exposed to different social conditions, which experimentally manipulated the experimenter's responses to infants' holdouts, and infants' reactions were recorded, coded and analysed using regression models. Secondly, how do these gestures mediate caregiver linguistic input during joint attention interactions? Chapter 3 presents a paper which examined how the type of deictic gesture produced by 11 month old infants influenced both the duration of interactions, and the type and number caregiver linguistic responses. Fine-grained coding of 120 video recordings of infant-caregiver interaction during naturalistic play was conducted, and multiple regression analyses were used to assess the predictive relations between type of gesture and the interaction qualities. Finally, what factors help caregivers to detect these gestures and other communicative cues during joint attentional interactions? Chapter 4 presents the third paper, which investigated the relationship between the level of experience in child development, and the ability to assess and identify features of recorded infant-caregiver interactions containing a gesture, using a questionnaire method. Responses were quantified and analysed using regression models. Taken together, the results indicate that prior to 12 months, infants' holdout gestures appear to reflect similar communicative motives to the pointing gesture. Furthermore, the types of gesture produced by infants influence the nature of their interactions and caregiver input during naturalistic play, and the ability to identify these communicative gestures, and other features of joint attention, is related to the level of experience infant development. These findings suggest that, before 12 months, infants possess some of the basic cognitive skills which are unique to human communication, and the development of these skills may be socially mediated. Chapter 5 considers the implications of these findings with reference to theoretical and practical implications for research and policy. Specifically, I consider how these findings fit into the social pragmatic approach to communication, and provide an explanation for the different patterns of results. Finally, I outline limitations of the current research and suggest some future directions for study.