This study investigated the potential interrelationship between parental (maternal) and expert assessments of the expressive and receptive language skills of 12- to 18-month-old children. The language activities of 27 children were monitored by their mothers (MCDI scale: Lyytinen, 2000. "Varhaisen kommunikaation ja kielen kehityksen arviointimenetelmä." Jyväskylän yliopiston lapsitutkimuskeskus ja Niilo Mäki Instituutti. Jyväskylä: Yliopistopaino. [An assessment tool for early communication and language development] Jyväskylä: University Press) and trained researchers (Bayley Scales III: Bayley, 2006. "Bayley III Scales of Infant Development. Administration Manual." San Antonio, TX: Psychological Corporation). First and foremost, the results showed that parental and expert assessments of different aspects of child development were in accord, even after controlling for the child's age. Covariance modelling confirmed the strong concordance between maternal and expert assessment of both aspects of early language development. Furthermore, maternal age did have an effect on the child's receptive language, according to experts' assessments. Gender or maternal education level did not have an impact on language skills as measured by Bayley assessment. Parent-reported dyslexia in a close relative was also taken into account.