Ethnomethodology (EM) and Conversation Analysis (CA) were founded, respectively, by Harold Garfinkel and Harvey Sacks in the 1960s. EM is a wide-ranging sociological investigation of social actions of all kinds. CA developed out of EM with a focus on natural language-use in actual, ‘naturally occurring’ occasions of social interaction. In a co-authored article published in 1970, Garfinkel and Sacks contrasted their research to what they called “constructive analysis”: the systematic substitution of theoretical and methodological constructs for the activities and expressions that organise social activities on particular occasions. The alternative that Garfinkel and Sacks developed eschewed constructive analysis in favour of the careful study and description of how ordinary activities are enacted and intelligible as they are produced by competent “masters of natural language”. As briefly set out in this introduction, this book was written to critically address selected trends in the past half-century that have gradually, and sometimes eagerly, introduced constructive analysis into EM and CA, and to encourage a return to the radical programme that Garfinkel and Sacks set out.