Economic theory generally treats the duration of a vacation as a constraint on demand (Varian, 1987) imposed by available time. In contrast, in this paper, we show that the length of stay is a determinant of destination demand more than a demand constraint, that is largely explained by the cost of travel, and moderated by the perceived characteristics of the destination, publicity, and the socio-demographic profile of the tourist. We estimate a heterogeneous survival model to measure the relationship between vacation length and covariates. The empirical application was carried out in Portugal on a sample of individuals traveling to Latin America on charter flights. The paper discusses the policy implications of the research findings.