Communicative Development Inventories (CDIs) were collected from
669 British children aged between 1;0 and 2;1. Comprehension and
production scores in each age group are calculated. This provides
norming data for the British infant population. The influence of socio-economic group on vocabulary scores is considered and shown not to
have a significant effect. The data from British infants is compared to
data from American infants (Fenson, Dale, Reznick, Bates, Thal &
Pethick, 1994). It is found that British infants have lower scores on both
comprehension and production than American infants of the same age.