Using Critical Discourse Analysis and Foucaultian Discourse Analysis, this study applies postcolonial theory to an examination of the discourses of wide-scale reading and writing assessments in Saskatchewan. The study provides answers to three questions examining how the discourses of wide scale assessments in reading and writing construct disadvantages for First Nations and Métis students and simultaneously construct advantages for white settler students. The research data includes the publicly available Assessment for Learning instruments, handbooks, pre-assessment materials, scoring guides and reporting documents for 2005 through 2010, a total of 177 documents. The analysis indicates that there are at least four distinct discourses within the Assessment for Learning materials that are made available for colonial knowledge production and power relations. These discourses can be identified as: linking reading and writing proficiency to becoming a successful and productive member of society; valuing the possession of a particular set of reading and writing strategies as indicative of reading and writing proficiency; espousing a set of common experiences and knowledge among all students at a grade level; and placing white settler English above all other varieties of English as the norm against which student work is measured, reinforcing the dominance of white settler language and culture over all other languages and cultures in Saskatchewan. The discourses of the provincial Assessments for Learning privilege students who come from white settler backgrounds while First Nations and Métis student interests are marginalized as are the interests of other linguistic minorities including Hutterian students and new Canadian students who do not speak the same variety of English as do the local white settler students. There are ways in which each of the four discourses can be troubled and countered and a set of 13 recommendations has been made to disrupt these discourses and put in their place new discourses that do not marginalize minority students. These recommendations include developing a set of shared beliefs around what the goals of education are and how achievement of those goals should be measured at a provincial level; arriving at a set of indicators and measures, acceptable to all stakeholders, to use in reporting on student achievement in reading and writing in Saskatchewan; constructing assessments that connect to curricular content common to all Saskatchewan students; providing student choice in assessment items; the development of a tool or set of tools for examining the discourses of all parts of the assessment materials for colonial knowledge production and power relations; and the review and revision of Saskatchewan curricula with a view to countering and troubling discourses found within the PreK-12 curriculum documents that are similar to those identified in the assessment materials.