The purposes of this study was to examine the mediating impact of floor noise complaints outcome expectancy, between negative reciprocity beliefs and floor noise complains. The author administered the Negative Reciprocity Beliefs Scale, the Floor Noise Complaints Scale, and the Floor Noise Complaints Outcome Expectancy Scale to 195 adults living in apartments and multi-unit housing. Results are as follow. First, negative reciprocity beliefs have a significant positive correlation with floor noise complaints. Second, negative emotion decrease expectancy, has a significant positive correlation with floor noise complaints. Third, negative evaluation decrease expectancy, has a significant positive correlation with floor noise complaints. Fourth, negative emotion decrease expectancy, mediated the relationship between negative reciprocity beliefs and floor noise complaints. Fifth, negative evaluation decrease expectancy, did not mediate the relationship between negative reciprocity beliefs and floor noise complaints. The theoretical and practical implications and limitations of this study are discussed.