Charting the dynamic character of mother-infant interaction requires using observational systems of sequential coding in real time. A longitudinal study was designed to approach maternal sensitivity in a more complex way using sequential analysis. The study was conducted with 20 high- and 20 low-risk mothers and their infants (aged: 3, 12 and 15 months) to examine the relation among mothers' risk status for physical abuse and their maternal interactive profiles, using micro-social sequential analyses, and the subsequent quality of attachment developed by their children at 15 months of age. Results showed significantly different timings in maternal responses in high- and low-risk groups, that the high-risk mothers were less sensitive: more intrusive and less discriminate regarding their infant's behavior. Significant differences between groups were also found after infant difficult behavior. High-risk mothers' infants were significantly more likely to develop insecure attachment. Sensitivity is proposed as a constellation of timings in early mother-infant interaction.