Jon Agar will introduce the concept of working worlds, illustrate how they can be used to think about past and present science, and identify some problems and issues. In a recent historical survey of science in the twentieth century, I devised a concept 'working worlds' which I think helps understand science's relationship with its broader context. Working worlds are arenas of human action that generate problems. The intuition was that science does not operate in a featureless, level environment; rather it responds to an uneven, given landscape of which working worlds are the major features. Our lives, but especially our sciences, have been organised by our orientation towards working worlds. In this seminar I will introduce the concept of working worlds, illustrate how they can be used to think about past and present science, and identify some problems and issues.