This paper focuses on the role of the estrangeirados ('Europeanized' intell
ectuals) as significant diffusion channels for the new scientific and techn
ological ideas and practices stemming from the Scientific Revolution and th
e Enlightenment. A definition of 'network' is introduced in this paper as a
methodological tool to characterize the estrangeirados. We argue that give
n their heterogeneous social origins, backgrounds and careers, they should
not be seen as a homogeneous group. Rather, they were part of a fluid netwo
rk, although they did not consider themselves as such. What they definitely
shared was a common scientific culture. Analysis of the links they establi
shed on a voluntary and often informal basis accordingly enables us to iden
tify the aims and strategies deployed to introduce the new sciences in 18th
-century Portugal, and to understand better why their reforming endeavours
had so little practical impact. In effect, the estrangeirados formed an eli
te which remained marginal to Portuguese society at large. In many instance
s their political options and their links to central power made them vulner
able to political and religious persecution. This considerably undermined t
heir agenda, which aimed at bringing the country into the forefront of adva
nced European nations.