Epistemology is a cross area between humanities and sciences, addressing the issues related to the meaning of the knowledge humans attain, and analysing the details and power of the methods through which it is attained. While the epistemology of science has been the object of investigation since ancient times (when science was part of philosophy), specific attention to the epistemology of engineering is recent. The present chapter aims at offering an overview of core issues pertaining to the epistemology of engineering, highlighting their connections with the epistemology of science while also emphasising the specificities of their connections with engineering practice—an aspect that is fundamental because the practical character of engineering determines the way in which it utilises theory, modelling and experiments in the design process.