Post-production services, such as sales, distribution, and maintenance, comprise a crucial element of business activity. A foreign firm faces a higher cost to perform such services than its domestic rival because of the lack of proximity to customers. We explore an international duopoly model in which a foreign firm can reduce its cost for post-production services by foreign direct investment (FDI), or alternatively can outsource such services to its domestic rival. Trade liberalization, if not accompanied by liberalization of service FDI, can hurt domestic consumers and decrease world welfare, but the negative welfare impacts can be mitigated and eventually turned into positive ones as service FDI is also liberalized. This finding yields important policy implications, given the reality that the progress of liberalization in service sectors is limited compared to the substantial progress already made in trade liberalization.