Recent theoretical contributions have suggested peer-group effects as a potential explanation for several puzzles in macroeconomics but their empirical relevance for intertemporal consumption choice is an open question. We derive an extension of the standard life-cycle model that allows for consumption externalities. In this framework, we propose a social multiplier approach to distinguish true externalities from merely correlated effects. Estimating our model using US panel data, we find strong predictable co-movement of household consumption within peer groups. Although much of this co-movement reflects correlated effects only, there is statistically significant evidence for moderate consumption externalities across several plausible peer-group specifications.