Understanding and overcoming challenges in times of personal or global crisis-Editorial on the Special Issue on Loneliness and Health.

The ever-present interest in loneliness has increased during the last decade. Although loneliness is generally not as prevalent as other topics and not among the top 5 most read papers in the journal Applied Psychology: Health and Well-Being, it is closely connected to topics therein, such as well-being and health. Conceptualizing loneliness as indicator of risk, it may function as a cue for action. Accordingly, understanding loneliness, its development, prevalence, effects, and how to support individuals to prevent or overcome loneliness is key and the main aim of this special issue. Therefore, theories and models are reviewed in this paper and synthesized together with other aspects relating to the field of loneliness research and intervention. Accordingly, we propose an agenda including key determinants (e.g., risk groups), how to proceed (various research methods), intervention components (e.g., behavior change techniques, SDGs), and how to perform dissemination (open science practices, co-creative approaches, etc.). The original studies in this special issue provide stimulating examples. Moreover, the commentaries give new insights and inspiring ideas. Overall, this special issue aims to give readers a lens with which to re-examine their own research, enable innovation, and empower addressing loneliness and its interconnection synergistically.