Dialogues of sets of socially similar twins are studied. The opinion that twins have slower syntactic development than non-twins is seriously questioned. Dialogues with twins saying the same utterance together, correcting each other, quarreling, playing verbal games, etc. are analyzed in their deep structure. (SCC)

This paper attempts to demonstrate that: (a) syntax is dependent on factors of cognitive and non-cognitive meaning; and (b) criteria for linguistic competence can only be fully met when full command of cognitive and non-cognitive meaning is present. Results have implications for future models of language and language acquisition. (CHK)