We video-recorded 22 mother-infant dyads at nine months, 12 of which had mothers with secure attachment models and 10 with insecure attachment models; to evaluate their emotional regulation and their styles of interaction with the objects, analyzing both the duration of the behavior of the two partners and their association in sequence. The secure mother dyads had a greater overall duration of affective matches with more positive and neutral matches than insecure mother dyads who spent more time in negative matches. Significant differences between the groups emerged also in relation to different mismatches. Furthermore, the secure mothers spent more time in play undertaken by the infant while insecure mothers spent more time in interaction not focused with respect with infants' activity. The quality of the attachment model of the mothers appears to affect the dyads' regulation, showing itself in the insecure mother dyads greater difficulty in mutual regulation and in the regulation of negative emotions.