As a modus operandi for researchers, open science involves sharing knowledge, data and tools in open collaboration and with all relevant actors. This is why it is important to identify and understand how open science impacts research. The EU-funded PathOS project will identify and quantify the key impact pathways of open science relating to the research system and its interrelations with economic and societal actors. The project will introduce a new understanding of open science to bring a common understanding on the system dynamics. It will also measure open science’s impact not only in the field of science but in the economy and society. PathOS will also develop innovative tools and methods to study the causal effects of open science.