Introduction: This study analyzes the use that the main NGO in Chile and Spain make of their profiles on Facebook and Instagram. Specifically, we study how they manage their public presence on these social networks, what issues they focus their activity on, how they are connecting with their audiences and the engagement they achieve. Methodology: the content analysis of the publications made by 50 NGO during a month has been used, taking into account quantitative and qualitative variables; the sample has been made up of 25 organizations from each country, selected by means of a non-probability sampling according to predefined criteria. Results: a total of 2,103 publications have been analyzed, which show that Facebook is the most used network, especially in Spain, and also the network with the largest number of followers; the use that NGO give to their profiles is basically informative, but there are differences between Spain and Chile and also by sector of activity of the organizations; the most used format for posting is text and notably the use of hashtags; the most common topics deal with the activities and projects of the NGO with a formal tone. Discussion: taking into account the social nature and the need to generate dialogue and connection with society, NGO should make more effort in their social media profiles given the scope and potential for generating engagement with their audiences. Conclusions: the communication strategies of the NGO in social networks do not take advantage of the power that these channels have to dialogue and establish relationships of trust with their audiences.