Extant literature on consumer engagement has focused on positive manifestations of the construct, rather than on its negative dimension. Yet, many brand interactions are negative in nature. The purpose of this conceptual study is to develop a typology of negative engagement behavior in social media by using the multi-grounded theory (MGT) approach on a sample of 12,429 tweets extracted from Twitter. The analysis shows that negative engagement behavior with a brand or service provider as the object focus or target can be categorized according to (a) the manifestation of the negative engagement and (b) the emotional intensity of the negative engagement. Four categories of negative engagement behavior (NEB) were identified. These include negative review writing, justice-seeking complaining, retaliation acts, and firestorming. The study concludes that an understanding of the different categories of negative engagement in social media is essential if service providers are to effectively address and respond to different forms of consumer sentiment.