Loneliness is the emotional response to the discrepancy between desired and available relationships. As people grow old, the likelihood of experiencing age-related losses increases. Such losses may impede the maintenance or acquisition of desired relationships, resulting in a higher incidence of loneliness. This pilot study examines how loneliness relates to age-related losses, hopelessness, self-transcendence, and spiritual well-being in a convenience sample of 107 adults aged 65 years or older. The collective utility of the independent variables in predicting loneliness was investigated by means of a regression decision tree with an automatic random subset crossvalidation procedure. This procedure explained 46% of the variance. Higher scores for age-related losses and hopelessness were associated with higher loneliness scores. Higher scores for self-transcendence and existential spiritual well-being were associated with lower loneliness scores.