This work aims to analyse the effects of complexity on decisions and learning in project-based organisations. Complexity is widely acknowledged as one of the main characteristics affecting project outcomes. We investigated factors giving rise to it and the subsequent organisational learning as new and codified knowledge to innovate project operations and we based our analysis on data collected from a sample of vessels projects in a leading company of shipbuilding. Results show that projects with a medium level of complexity (where factors such as variety of technologies and scale were limited but present) enabled learning and better subsequent operational decision-making
