Abstract.When entering into a negotiation, individuals have the choice to enact a varietyof communication styles. We test the differential impact of being “warm and friendly” versus “tough andfirm” in a distributive negotiation whenfirst offers are held constantand concession patterns are tracked. We train a natural language processing algorithmto precisely quantify the difference between how people enact warm and friendly versustough andfirm communication styles. Wefind that the two styles differ primarily in lengthand their expressions of politeness (Study1). Negotiators with a tough andfirm com-munication style achieved better economic outcomes than negotiators with a warm andfriendly communication style in both afield experiment (Study2) and a laboratory ex-periment (Study3). This was driven by the fact that offers delivered in tough andfirmlanguage elicited more favorable counteroffers. We furtherfind that the counterparts ofwarm and friendly versus tough andfirm negotiators did not report different levels ofsatisfaction or enjoyment of their interactions (Study3). Finally, we document that in-dividuals’lay beliefs are in direct opposition to ourfindings: participants believe thatauthors of warmly worded negotiation offers will be better liked and will achieve bettereconomic outcomes (Study4).