My current research explores the influence of formal and informal organisational communications on attitudes to compliance and non-compliance with safety regulations in the UK chemical processing industry . Chemical processing organisations are not mono-cultures but comprise collections of sub-cultures characterised by hierarchical and functional differences. Within these complex systems, each sub-culture has its own self-renewing norms which in turn influence the other sub-cultures. Each signal sent out by a sub-culture may be heard, adapted and adopted by other sub-cultures. As subtle changes in compliance are left unchallenged or without consequence, the adapted practice becomes the new norm. This unspoken shift in behaviour is termed ‘practical drift’. My research explores the complex adaptive system antecedents of non-compliance.