ABSTRACTThe relationship between age and loneliness is intriguing. While loneliness has been widely perceived as a problem of old age, there is evidence suggesting that adolescence is the peak age for experiencing loneliness and there are demonstrable variations between nations in reported rates of loneliness. However, comparative data for examining both the prevalence of loneliness across age groups and across nations are sparse. As the first phase of a larger project, we explore the prevalence of loneliness across different age groups in 25 European nations, with a focus on people of an advanced age. After discussing issues of comparability, we present our empirical findings employing data collected in the third round (2006–07) of the European Social Survey (total sample size 47,099, age range 15–101) which included a ‘self-rating’ loneliness scale. Our results suggest that the prevalence of loneliness does increase with age for the combined sample. However, the nation in which one lives shows a greater impact than age on reported levels of loneliness, with Russia and Eastern European nations having the highest proportions of lonely people (about 10–34% for different age groups) and Northern European nations the lowest (mostly below 6%). Possible explanatory factors are identified and discussed, which provides the groundwork of a subsequent and formal study.