Many urban activity and location decisions can be viewed as the outcomes of sequential search processes. In this paper are addressed the special econometric aspects associated with the analysis of observations on such processes. Four distinct informational situations of particular relevance to search phenomena are identified, each one corresponding to different data-availability conditions. The likelihood functions appropriate for estimating the parameters of search models in each one of those informational situations are derived. Special cases in which these likelihood functions appear to be computationally tractable are also indicated in the appendix.