This study explores the hypothesis that the existence of a short sensitive period for lower-level speech perception/articulation skills, and a long one for higher-level language skills, may partly explain the language outcomes of children with cochlear implants (CIs). The participants were fourteen children fitted with a CI before their second birthday. Data about their language skills and the environmental conditions (e.g. Family Involvement in rehabilitation) were obtained over a period of three years. Age at implantation correlated exclusively with the ratio of errors of place of articulation, a phonological feature for which CIs provide insufficient information. The degree of Family Involvement was significantly correlated with the remaining language measures. We conclude that small plasticity reductions affecting lower-level skills may partly explain the difficulties of some CI users in developing language.