Purpose – The purpose of this paper is to study factors affecting consumers’ liking and commenting behavior on Facebook brand pages, and to analyze the mediating role of mode of interaction on relationships between personality traits and liking/commenting behavior. Design/methodology/approach – Data were collected using an online national survey from 269 respondents, ages between 18 and 32. The hypotheses were tested using structural equation modeling. Findings – Results support nine of ten hypotheses with significant relationships between analyzed constructs. It was found that two different modes of interaction acted as mediators between three personality traits and liking/commenting behavior on Facebook. Research limitations/implications – This study only included liking and commenting behavior on Facebook. Future studies could extend the conceptual model by including sharing behavior and other personality traits that were not included in this conceptual model. Practical implications – The findings have several implications for brand managers with respect to their social media strategies and give them guidance in achieving better customer engagement on Facebook. This research is an important step in understanding the factors affecting consumers’ Facebook behavior and useful for practitioners intending to use Facebook as part of their marketing strategy. Originality/value – The study provides a comprehensive framework to understand consumer engagement on Facebook by including specific types of Facebook behavior, three personality traits and two modes of interaction that consumers have in social media.