The Web 2.0 technology structure that activates users paved the way for the "direction of communication, interaction, dialogue" of discussions in the public relations literature. Examining the concept of dialogue specifically for NGOs may be important in terms of developing social media usage. As a social media platform, Instagram is not adequately addressed in the literature in terms of dialogic principles. For this reason, the aim of this study is to determine how environmental NGOs use the principles of dialogic communication, public relations models, and interactivity in their Instagram posts. It is found that the most popular environmental NGOs are TEMA, Greenpeace, and WWF, and their posts have been evaluated through content analysis. In the process, their posts have been examined according to Kent & Taylor's dialogic principles. In addition, the categorization and ratio calculations have been made according to Grunig & Hunt's four models of public relations, and interaction rates have been calculated according to Avidar's responsiveness pyramid. Findings suggest that environmental NGOs use Instagram by reflecting dialogic communication principles. For public relations models, being asymmetrical with a high frequency and weakness of interaction ratios begs the question: can dialogic principles be performed by a one-sided information flow and low interaction?