Homotheticity induces a dramatic statistical bias in the estimates of the intratemporal and intertemporal substitutions. I find potent support in favor of nonhomotheticity in aggregate consumption data, with nondurable goods being necessities and durable goods luxuries. I obtain the intertemporal substitutability negligible (0.04), a magnitude close to Hall’s (1988) original estimate, and the intratemporal substitutability between nondurable goods and service flow from the stock of durable goods small as well (0.18). Despite that, due to the secular decline of the rental cost, the budget share of durable goods appears trendless.