Maternal and infant interactional characteristics in early infancy were investigated in order to examine their causal relationship with later attachment as assessed in the Strange Situation. Although the results of rating for maternal variables at four months of age exhibited significant differences between the set (S1) composed of attachment type B subgroups one through three and the set (S2) composed of B subgroup four and group C, no significant differences were discovered between types B and C. As for infant variables, only negative reactions to the stranger showed significant differences between S1 and S2. Individual differences in temperament-related reactions were found between B and C. In addition, several mother-infant "meshing" patterns were discovered. Interaction of S1 mothers and infants meshed very well, whereas S2 mothers and infants tended to show "out of tune" patterns due to mother's inadequacy in interacting, or infant's negative affect and behavior. Results are interpreted as suggesting that later attachment may be determined not by maternal variables but by "meshing" or "the compensative function in each partner." Infant temperamental disposition, it is thought, especially may function during interaction with the mother; the temperamental tendency then becomes apparent in a critical or stressful situation. (Author/RH)