By using data relating to Nigeria, this paper reports the results of analyses directed toward examining the validity, in a Third World context, of the postulate advanced by a number of authors that the amount of time spent traveling has certain stable properties and can serve, therefore, as an alternative parameter to trip rate for use in deriving estimates of future travel demand. Analysis of relations between traveler characteristics and time-budget-expenditure patterns reveals the significant influence of engagement in supplementary employment on both travel and nontravel activities. Explanations are put forward to account for similarities and differences found in patterns of daily travel-time variation displayed by residents of Lagos and Ibadan. These explanations lead to the formulation of tentative hypotheses about the relations between different aspects of travel-time variation and transportation system characteristics as a settlement evolves. In particular, it is suggested that mean daily travel time is likely to be reduced as a result of implementing measures introduced to resolve problems diagnosed during a period of transportation system overload. Attention is drawn to the implications of this and other relations for transportation modeling and time-valuation practice in Third World cities.