This article explores the effectiveness of a 416-hour professional programme intended to support 5010 Kazakhstani teachers in shifting to teaching their subjects through English. Document analysis describes the perceived intent of the course and how that is reflected in the course description and guidelines given to trainers. Document analysis is triangulated against 18 hours and 28 minutes of interview and focus group data from 74 participants. Data were processed through NVivo for thematic analysis to form and develop emergent themes until saturation of the data was achieved against these themes. Research findings suggest that the implementation of the professional development programme as a centralised policy initiative has been approached as a mechanical, one-size-fits-all process of mainstreaming a nationwide teacher development scheme across all regions of the country. There is a considerable divide between programme intentions and delivery. Content and Language Integrated Learning (CLIL) which is a stated guiding principle, is largely absent from documents and interview data. Assessment has been flawed from the participants' perspective who do not have an objective measure of their progress.