Large corporations are increasingly implementing lasting corporate improvement programmes based on lean thinking in their global production networks. The aim is to improve operational efficiency by sharing best operational practices and foster continuous improvement among all subsidiaries. However, it remains an open question why implementation success differs substantially across cultures and sister plants for most companies. We review the existing literature on improvement programmes and culture, and compare the current state of the art with unique quantitative data from 80 factories belonging to two global manufacturing companies. We surprisingly find no explanatory power in national culture (measured with Hofstede’s model) and propose that other factors such as the organisational culture and the strategic role of the plant matters far more.