The subject matter of this thesis are some aspects of the expression of explanations in spoken discourse. The study of explanations has occupied the attention of many researchers in social psychology and in neighbouring disciplines; the study of talk has occupied an even greater number. In the thesis I try to integrate certain areas of these two fields. Chapter one sketches the history of the concern with language which has characterised developments in the social sciences this century. This chapter is incidentally an introduction to some of the key themes of the thesis and to why I think research based on naturally occurring discourse is important. Research on explanations in social psychology has been dominated by research which has gone on under the heading of attribution theory. In chapter two I address a controversy in the application of concepts drawn from attribution theory to clinical psychology, namely whether or not people have fixed styles in the way that they attribute causes for outcomes. Studying family therapy sessions and interviews with parents with a coding procedure I show that the variety of possible styles is broader than has been suggested previously. Chapter three further pursues causal expressions as cases of explanations by asking what a causal statement is. The chapter opens with a discussion of how causes relate to reasons concluding that reasons are a species of cause. I then go on to use data from earlier work to study what expressions speakers use to make causal utterances. The direction of enquiry has been to suggest that rather than studying causal beliefs it is causal utterances that are under study. An utterance is, if you like, "situated", that is to say, what a speaker says is context-bound. I talk of "communicative constraints" operating here. Chapter four reviews some work in the study of conversation with an eye to elucidating the sense in which a speaker's utterances are a product of the situation in which they occur and to look at the researchability of this intuition. Practical and conceptual reasons suggest that the approach generally known as conversation analysis stemming from the study of ethnomethodology is the most interesting and fruitful way toproceed (in this context). Chapters five and six report studies of a computing advisory centre showing 1, the range of accounting procedures which occur as part of the business-at-hand in these sessions, 2, how speakers' utterances, can change within a single conversation. Chapter six looks at the integration of non-vocal behaviour and by considering data on this argues that the idea of normativity, rather than a quasi grammatical notion, is the appropriate level of explanation for the regularities which we find in human interaction. In moving away from beliefs as the object of analysis I could be accused of taking an anti-cognitive stance. Chapter seven explores cognitive versus interactional perspectives in communication. Chapter eight reflects on the approach which I have adopted and suggests how inspite, indeed through, its focus on situational events an account of the capacities drawn on in offering explanations can itself illuminate phenomena seen as beyond its grasp