In this article, we analyse experiences of loneliness among older people living alone. Current knowledge suggests that loneliness is a significant social issue that can compromise health and wellbeing, and that seniors living alone are at a higher risk of loneliness. Based on a qualitative methodological approach and semi-structured interviews conducted with 43 people aged 65 or over living alone in Montreal (Quebec, Canada), this study sought to understand how they perceive, reflect on and react to loneliness. The results show that these seniors perceive loneliness as a dynamic, and rarely static, experience, which has a very different significance, depending on whether it is chosen or circumstantially imposed. The experience of loneliness recounted by the seniors we met is characterised by its heterogeneity, and involves, to varying degrees, their relationship to themselves (solitude), to others (family (and friends) loneliness and loneliness in love) and/or to the world (existential loneliness and aloneness). Lastly, our analyses highlight how social factors, such as age, gender, marital status, social network and socio-economic conditions, shape the experience of loneliness among seniors. These factors also influence the strategies that seniors develop to prevent or alleviate loneliness, strategies that yield very mixed results.