© Ulbe Bosma, 2015.Existing literature and available demographic data suggest a strong divergence between Java and the Outer Islands with regard to nineteenth-century demographic trends. In this article, I argue that such a divergence is highly plausible, because of the inchoate vaccination efforts against smallpox in the Outer Islands in contrast with those on Java during the nineteenth century. I suggest that further research is needed into other factors that might also have contributed to the perceived divergence. These include relatively low birth rates in the Outer Islands as well as the ubiquity of slavery in this part of the Indonesian archipelago and its exposure to slave-raiding and the slave trade. The article concludes by arguing that, in all likelihood, demographic growth was very limited in most, but not all, of the Outer Islands up to the late nineteenth century.