This paper reports on a longitudinal study involving 48 mother-infant dyads that attempts to explore the role of the caregiver-infant interactional environment in determining cognitive functioning as related to an understanding of environmental contingencies. The present report includes (1) a progress report to date of the longitudinal data collection of the Origins of Infant Competence; (2) a description of the inter-observer reliabilities from the pilot study and the first phase of the longitudinal study; (3) description of the data-reduction scheme and computer programs devised to organize the observational data; (4) preliminary results of the pilot observational study that examined the (a) effects of infant state, caretaking setting, and maternal proximity on vocal behavior of infants and mothers; (b) patterns of maternal behavior in intervals antecedent and consequent to infant vocalization onsets; and (c) the temporal structure which characterized alternation of vocal activity between infants and mothers; and (5) a description of the sample for the longitudinal study. Appendices contain the observational code used, a computer program written for the data (56 pages), and materials used in contacting parents. (Author/SB)