Due to the increasing importance of acquiring technological tools in communication strategies, and while taking into account that non-Governmental Organizations (NGO) use Instagram as a potential artivist tool to disseminate their initiatives and needs, the present article aims to investigate the form and content of photographs published on Instagram during 2017 by the 20 most relevant NGOs at the international level. Specifically, we study the choice of formal elements, such as the design and editing, the intended purpose and feeling of the message transmitted in the photographs, as well as the type of actor or actors in the images (including their role, number, gesture, sex and age). In addition, we study the use and the engagement generated by children's images. Content analysis, non-parametric statistical analysis with Chi-square test and variance analysis (ANOVA) are used as methodologies. The results of the study show how prototypical images used by NGOs (young children enjoying the benefits of aid with positive appearance and gestures) present content and formats that do not correspond to the type of image that generates more engagement from the target audience.