The aim of this study was to evaluate if a diagnostic work-up should be recommended for 2-year-old children with developmental language delay (LD), or if the widely chosen "wait and see" strategy is adequate. Children with LD were identified in paediatric practices during routine developmental check-ups using a German parent-report screening questionnaire (adapted from the MacArthur Communicative Development Inventories). A standardized German instrument and the Netherlands version of Bayley Scales of Infant Development (2nd edn) were used to assess language ability and nonverbal cognitive development respectively in 100 children with LD (65 males, 35 females; mean age 24.7mo [SD 0.9]) and a control group of 53 children with normal language development (33 males, 20 females; mean age 24.6mo [SD 0.8]). Neurological and audiometric testing were also performed. Sixty-one per cent of the LD group had specific expressive LD and 17% specific receptive-expressive LD. In 22%, LD was associated with other neurodevelopmental problems, 6% showed significant deficits in nonverbal cognitive abilities, and in 12%, nonverbal cognitive abilities were borderline. Four per cent fulfilled the criteria of childhood autism. LD at 2 years proved to represent a sensitive marker for different developmental problems. Adequate early intervention requires a clear distinction between specific expressive or receptive-expressive LD and LD associated with other neurodevelopmental problems. Though catch-up development is to be expected in a substantial proportion of "late talkers", our data demonstrate that a general "wait and see" approach is not justified in young children with LD. A proposal for a rational diagnostic work-up is presented.