This paper studies how migration from a poor to a rich country affects key economic beliefs, preference parameters, and transnational household decision-making efficiency. The setting is the migration of Tongans to New Zealand through a migration lottery program. In a 10-year follow-up survey of individuals applying for this program, the study elicited risk and time preferences and pro-market beliefs. It also linked migrants and potential migrants to a partner household consisting of family members who would stay behind if the migrants moved. Survey participants played lab-in-the-field games designed to measure the degree of intra-family trust and the efficiency of intra-family decision-making. Migration provides a large and permanent positive shock to income, a large change in economic institutions, and a reduction in interactions with partner household members. Despite these changes, the study finds no significant impacts of migration on risk and time preferences, pro-market beliefs, or the decision-making efficiency of transnational households. This stability in the face of such a large and life-changing event lends credence to economic models of migration that treat these determinants of decision-making as time-invariant, and contrasts with recent evidence on preference changes after negative shocks.