Applying the framework of North et al. (2009, Violence and Social Orders: A Conceptual Framework for Interpreting Recorded Human History. Cambridge: Cambridge University Press), this paper analyses institutional and economic development in a new setting – the Grand Duchy of Lithuania between 1245 and 1386. Although remaining a fragile limited access order, Lithuania achieved positive institutional change. Its elite became more stable by restricting ruling privileges to the grand duke's family and integrating rival dukes through administrative positions and hereditary property rights. This arrangement encouraged land accumulation and productive activity over extraction, while the elite started providing better security to traders and craftsmen seeking to finance its war against the Teutonic Order. Synthesised material evidence reflects development at the extensive margin. However, health data shows no increase in average living standards, potentially due to population growth and inequality. Both sets of findings are consistent with the conceptual framework, as it expects fragile limited access orders to be underdeveloped from a static perspective, but improve following institutional development.