This paper provides experimental evidence suggesting that there are considerable differences in native language attainment, and that these are at least partially attributable to individual speakers’ experience. Experiment 1 tested high academic attainment (hereafter, HAA) and low academic attainment (LAA) participants’ comprehension using a picture selection task. Test sentences comprised passives and two variants of the universal quantification construction. Active constructions were used as a control condition. HAA participants performed at ceiling in all conditions; LAA participants performed at ceiling only on actives. As predicted by usage-based accounts, the order of difficulty of the four sentence types mirrored their frequency. Experiment 2 tested whether the less-educated participants’ difficulties with these constructions are attributable to insufficient experience. After a screening test, low scoring participants were randomly assigned to two training groups. The passive training group were given a short training session on the passive construction; and the quantifier training group were trained on sentences with quantifiers. A series of post-training tests show that performance on the trained construction improved dramatically, and that the effect was long-lasting.