This paper focuses on unsanctioned practice innovations (UPIs) and how they are generated and realised by those outside the senior ranks of an organisation. Through a longitudinal in-depth qualitative study of a multinational firm between 2001-2014, we discovered how deviance from formal procedural frameworks had diverse and often creative and productive effects that countered the constraints of transparency, legitimacy and top-down planning of practice innovations. Deviants enact a range of manoeuvres, often resulting in delegitimising prescribed practices and novel solutions to problems that an organisation encounters. We provide an analytical account of these UPIs, the manoeuvres necessary in their claims to legitimacy and the implications for more formal practice innovations.