GeneralizationOnly those children who reached criterion duringintervention participated in the generalizationphase. Both Valerie and Timmy exceeding criterionduring this phase (i.e., 16 and 18 combinationsand 17 and 23 combinations, respectively). Thus,Valerie and Timmy (a) generalized production ofmulti-symbol messages to new play routines,and (b) did not require aided AAC models toproduce multi-symbol messages within these playscenarios.