This is the first large-scale study to investigate the seroprevalence of varicella zoster (VZV) in the general population of England and Wales. The study focused on those aged 1–20 years, that age group in whom most infections occur. Prevalence rose rapidly with age, with 53% of children showing evidence of prior infection by the age of 5 years and most young adults having experienced infection. In addition to using a fixed cut-off recommended by the manufacturer, a mixture modelling technique was also used to define the proportion of the population seropositive in each age group. This was shown to be a more accurate approach to categorizing data from an epidemiological perspective.