In critical discourse studies, educational practices are often used as examples of how social power operates in social practice (e.g. van Leeuwen, 2008 p 3; Rogers et al, 2004; Fairclough, 2003 p. 25; Fairclough, 1992 p. 134; Fairclough, 1989 p. 26) However, and not least from an L1 perspective, further research is needed concerning the roles of discourse and power structures within the classrooms and particularly their implications for (participation in) writing instruction practice in primary school years. The main purpose of the study is therefore to conceptualise early school writing instruction (with 6 and 7-year-old students) from a critical discourse analytical perspective (Fairclough, 2003) and in doing so unveil how social power permeates the discourse practices of early school writing and how its effects on writing instruction may be understood. The theoretical and methodological framework is based on Fairclough’s (2003) three-dimensional model for textual analysis in three phases (description, interpretation, and explanation). The CDA approach show, through empirical examples, major differences in the effects of power in discourse in two L1 writing classrooms, shaping the discourse practice in various ways. The study shows how a CDA framework may enable a deeper understanding of how social power operates in and behind the discourse of writing instruction in early school years. In this conceptualisation of early school writing instruction from a CDA perspective, it is evident that the classroom is a site of power struggles with effects on discourse and where discourse practices, in various ways, (re)construe both the social world of the classroom as well as what is being taught. The article further provides an example of how a CDA analysis may be operationalised, and in particular in an educational setting in primary school years.