Social isolation is a deprivation of social connectedness. It is a crucial aspect that continues to be named by people as a core impediment for achieving well-being and as a relevant factor for understanding poverty. However it is not routinely included in surveys that provide data on multidimensional poverty measurement. Although the challenge of measuring social connectedness is daunting, this paper argues that existing research in several fields provides solid ground for the construction of basic internationally comparable indicators that measure specific aspects of social isolation. In particular, this paper synthesises the relevant literature on the measurement of social isolation and related phenomena, and on the basis of this synthetic review, proposes a module of indicators to measure social connectedness that could be feasibly incorporated into an internationally comparable multi-topic household survey.