Reported here are developmental relations between language and thought in the one-word period. However, these relations are different from those discussed in classic developmental theories like Piaget's. Piaget proposed that deferred imitation emerged at about 18 months, in synchrony with other aspects of the "semiotic function" including spoken language. Our findings establish deferred imitation in 9-month-olds. Thus, the emergence of deferred imitation is not a cognitive correlate of language; it is exhibited before language is acquired. We develop the "specificity hypothesis" concerning the interrelation between certain aspects of early semantic and cognitive development. Data are adduced showing highly specific relations between: (a) categorization and the onset of the "naming explosion," (b) object permanence and the use of words encoding disappearance, and (c) means-ends understanding and words encoding success and failure.