Understanding the demography of threatened taxa is essential for formulating effective management strategies for their conservation and for making predictions about their long-term prospects. With fewer than 25 breeding pairs in the current wild population, the Helmeted Honeyeater (Lichenostomus melanops cassidix) is one of the most threatened birds in Australia. Demography of the sole wild population of the Helmeted Honeyeater was investigated by monitoring 526 nests between 1984 and 1996 and 324 colour-banded birds between 1984 and 2008. Throughout the study, the population was effectively closed, there being no evidence of immigration or emigration. Mean survivorship of nests from laying to fledging was 0.17, and mean survivorship of juveniles (from 40 days to 1 year of age) was 0.63. Weighted mean annual survivorship of adult females and males was 0.75 and 0.81 respectively. The population showed little between-year variation in annual productivity and survivorship, with sufficient recruitment for positive population growth. In general, the population dynamics of the Helmeted Honeyeater fit the pattern of an 'old endemic' Australian passerine, with low survival of eggs and chicks, extended parental care of juveniles and high survivorship of juveniles and adults. Eggs and chicks that would not naturally survive are a resource that may be used to assist recovery of the population.