In this paper a simple model of foreign direct investment is developed and
tested on investment flows from the USA to Mexico between 1967 and 1994 usi
ng cointegration analysis. Domestic demand and relative factor costs are fo
und to influence direct investment flows, suggesting support for both the '
cheap labour' and 'market size' hypotheses. The short-run dynamics of the m
odel indicate that exchange rate movements have an effect on the timing of
the investment decision.