Philosophiae Doctor - PhD / This research is in the area of child language acquisition, especially, acquisition of figurative language. It investigates how native Cicewa speaking children learn to interpret Cicewa idioms. This is done through examination of sociocultural contexts in which idioms are produced and consumed. It involves the identification of factors influencing children’s acquisition of idioms and strategies employed by children to interpret idioms. The study also investigates how children rerank language constraints in the process of acquiring Cicewa idiomatic meanings. The study is informed by two theories: Systemic Functional Linguistics (SFL) and Optimality Theory (OT). SFL is used to explore the sociocultural contexts within which Cicewa idioms are acquired, produced and consumed. It also helps to explain the social cultural factors influencing children’s choices of meaning options and idiom acquisition strategies. OT is used to establish how children rerank language constraints in the process of acquiring idioms in Cicewa with an aim to identify the developmental stages in idiomatic meaning acquisition. The study adopted cross-sectional and experimental designs. Experiments were conducted on 20 typically developing native Cicewa speaking children with ages 4, 6, 9, 12 and 14 drawn from Mpalume Village, in Chinamawali Township, Zomba Malawi. Deliberately developed stories, sentences containing idioms and idiom lists were used to collect data in five experiments. The data were analysed both qualitatively and quantitatively. Qualitative analysis involved identification of types of responses given by children, strategies employed by children to interpret idioms and factors that influence children’s interpretation and acquisition of idioms. Quantitative analysis was done using Statistical Package for Social Sciences (SPSS) to determine how often a response was given, differences in the responses given by children of different age groups and to establish if there was a relationship between idiom interpretation and the tested factors. The research finds that children produce more idiomatic interpretations when the idioms are presented in stories than when the idioms are presented in sentences and out of context. It also finds that idiom acquisition starts with idiom recognition at around 4 years and interpretation starts at around 6 years with a child interpreting idiomatic expressions involving daily activities of human experience. It also finds that 14 years is the age at which the child’s idiomatic knowledge starts to resemble adult’s knowledge although at this age acquisition of idiomatic meaning is still taking place. In addition, it identifies a number of strategies that children employ to interpret and acquire idiomatic expressions. Among the identified strategies ‘inferring from sociocultural context’ is the only successful strategy. Additionally, the thesis establishes that children learn first idioms that involve daily activities of human experience then idioms with clear cultural frames reference and finally idioms with obsolete cultural frames of reference. It also establishes that knowledge of the sociocultural context in which idioms are consumed is critical in idiomatic meaning acquisition. A child can have skills to use the contextual cues and have knowledge of the grammar but if s/he lacks the sociocultural knowledge cannot correctly interpret an idiom nor acquire it. It also establishes that the language constraints Full Interpretation and CONSISTENT are highly ranked dominating Relevance Principle at the initial stage in idiomatic meaning acquisition and that the two constraints are demoted as the child acquires idiomatic meaning. The thesis also identifies five developmental stages that children go through in idiom acquisition. These are Stage 1: 4 – 5 years, an initial stage in which a child is able to recognize an idiomatic expression as an instance of use; Stage 2: 6 – 8 years, a stage in which a child is able to interpret idioms of daily activities involving human experience when presented in supportive context; Stage 3: 9 – 11 years, a transitional stage in the development of idiomatic meaning in which a child is able to interpret idioms involving daily activities of human experience when presented without supportive context; Stage 4: 12 – 13 years, a stage in which a child is able to interpret idioms with clear cultural frames of reference when presented without supportive context and Stage 5: 14 years and above, a stage in which the child’s idiomatic knowledge is close to adults’ knowledge and a child is able to interpret idioms with absolete cultural frames of reference when presented without supportive context. The study makes a contribution to the idiom acquisition debate by pointing out that sociocultural knowledge is crucial in the acquisition of idioms thereby clarifying what goes on in the process of idiom acquisition. It has also identified and described developmental stages in idiom acquisition. The study is the first not only to use SFL, but more so in conjunction with OT to account for idiomatic meaning acquisition and interpretation. This eclectic mix of theoretical frameworks is novel and thus offers a new perspective of theorizing never done before. Thus, the thesis contributes to the development of linguistic theory, from both SFL and OT perspectives. Overall, the thesis concludes that children come to know an idiomatic expression as a text before they even understand the sociocultural context in which it is consumed. It argues that idioms are acquired as texts and they are acquired together with the sociocultural context in which they are acquired, consumed and produced, and therefore the sociocultural context forms part of the idioms.