This article offers a theoretical framework for studying loneliness among older people from a social problems perspective. The framework combines the constructionist approach to social problems (Spector and Kitsuse) and systems theory (Luhmann). Based on the first approach, we understand the social problem of loneliness among older people to be the result of claims-making activities by different key actors. These activities are guided by underlying moralities, causalities and solutions. With the second approach, we can explain how social problems are framed differently within different social systems. The proposed framework is primarily aimed at researchers studying social (in contrast to bio-medical or psychological) aspects of loneliness among older people. It helps not only to guide research designs in order to address conflicting perspectives, rationalities and interests but also to enable researchers to grasp fully how ‘loneliness among older people’ is attributed (potentially shifting) meanings through communicative acts by influential stakeholders in the ‘social problems industry‘. Combining constructionism and Luhmann's theory also helps to interpret and explain concrete claims-making concerning loneliness as a social problem. The argument in this article is illustrated via three different social systems: medicine, religion and economy. Loneliness among older people appears to be something different from each of these perspectives: as a matter of health and illness, of spirituality, and of incentives and commodities, respectively.