Chapitre d'ouvrage: That wage satisfaction depends on reference wage is now an acquis of the empirical happiness literature. Employees care about their coworkers’ wage. They compare to different notions of reference wage and suffer from disadvantageous comparisons, more than they enjoy advantageous ones. However, reference wage sometimes acts in a positive way, as a carrier of information. In terms of methods, the empirical literature has developed in three stages. First, it started by enquiring about the statistical association between a notion of reference wage (or reference income) as defined by researchers, and self-declared satisfaction. Second, some researchers tried to elicit the direction of income comparisons by including direct questions in large surveys of the population. Third, researchers attempted to provide experimental evidence of the causal effect of comparisons on satisfaction (beyond the simple statistical association) using natural, field, and lab experiments.