Research conducted into the demography of the Kingdom of Kongo some forty years ago, employing baptismal statistics left by missionaries, has been in need of revision thanks to challenges by more recent scholarship. This article revises the estimated population of Kongo by addressing these challenges, drawing on newly discovered documentary sources. Using this new evidence, the estimate for the kingdom's population in the mid-seventeenth century has been elevated from 509,000 to around 790,000. The original article's claims about levels of fertility and mortality have been retained. The article also addresses questions concerning the validity of missionary statistics and the impact of the slave trade, which was small before 1700 but then increasingly large thereafter, reaching very high levels by the early nineteenth century. While a quantitative estimate of the later population is not possible given the limitations of sources for this period, it is likely that the population of the kingdom fell as slave exports peaked.