The measurement of human behavior is a complex task, both for psychologists and human sciences researchers and with respect to technology, since advanced and sophisticated instruments may have to be implemented to manage the plurality of variables involved. In this article, an observational study is presented in which a quantitative procedure, the external variables method (Duncan & Fiske, 1977), was integrated with a structural analysis (Magnusson, 1993, 2000) in order to detect the hidden organization of nonverbal behavior in Italian and Icelandic interactions. To this aim, Theme software was introduced and employed. The results showed that both the frequency and the typology of gestures deeply change as a function of culture. Moreover, a high number of patterns was detected in both Italian and Icelandic interactions: They appeared to be complex sequences in which a huge number of events were constantly happening and recurring. In this domain, Theme software provides a methodological progression from the quantitative to the structural approach.