Acute and chronic ear problems can lead to hearing loss. Temporary and persistent hearing loss during early and mid-childhood can impact speech and language development, behaviour and other developmental milestones. There is some evidence that the consequences may be long-term in influencing outcomes related to behaviour, social interaction and mental health into adulthood. Unlike most birth cohort studies, the Avon Longitudinal Study of Parents and Children (ALSPAC) has repeated measured aspects of hearing and ear related signs and symptoms in considerable detail during childhood. This enables the identification of consequences and preventive features that can be considered. In this, the first of two Data Notes, we outline the information collected from direct assessment of the study cohort, between the ages of 8 months and 15 years. This includes features related to ear conditions and hearing ability, and indicates the variables derived and the frequencies of the results obtained during childhood and adolescence.