We present a corpus-based study of the Corporate Social Responsibility Reports issued by companies who operate in the Spanish Stock Market IBEX 35. Natural Language Processing methods are used for extracting informative collocations and measuring the textual complexity of these texts. Based on our results, we claim that (1) these reports are in general simpler and more redundant than general language, (2) there is a tendency towards the increasing use of the term sustainability to describe SR actions, and (3) integrated reports seem to be written for shareholders rather than the general public.