The use of pronouns shows the author’s intention to address the reading public or the presence of the target readership in texts. This paper focuses on second-person pronouns, which are especially revealing of the author`s desire to engage the reader by endowing on them an active role in the negotiation and construction of knowledge. For the same reason, we will also analyse the use of the word reader. Science writing is thus understood as a dialogue between the two groups of participants involved in knowledge creation. Two usages of you have been detected in previous works using the Coruña Corpus of English Scientific Writing (CC): general and dialogic. The former might be interpreted as a generic “one,” “everybody;” the latter, considered as an in-group strategy that embraces both the writer and the reader. The detailed analysis of the pragmatics of the second person pronouns and reader in Corpus of English Chemistry Texts (CEChET) and Late Modern English Medical Texts (LMEMT) will hopefully shed some light on the object-centred nature of scientific writing.