This chapter deals with the main methodological issues underlying the building of the SciE-Lex lexical database and discusses and justifies the information included. SciE-Lex was initially conceived as a response to the lack of reference tools that can help scientists write scientific papers in phraseologically competent and native-like English. While there are a number of specialised dictionaries that include specific terminological information, there is a shortage of writing aids that provide information about the use of non-technical terms in scientific genres. SciE-Lex aims at filling this gap by focusing on the description of general terms in scientific English. This article describes the two stages in the building of the database, the first one including morphosyntactic and collocational information, and the second one focusing on phraseological information.