BACKGROUND AND AIMS: In clinical practice, the status of living alone is often used as the only measure describing an older person's social network. We evaluated whether additional use of a brief social network measure provides relevant additional information in relation to social support and engagement. METHODS: Cross-sectional survey of 6982 community- dwelling adults 65 years or older living in London, UK; Hamburg, Germany; and Solothurn, Switzerland. Data were collected using the self-administered multidimensional Health Risk Appraisal Questionnaire. Multivariate models were used to analyse adjusted correlations between the two measures of social network (living alone status, risk for social isolation with marginal family and friend network subscales) and potential consequences of inadequate social network (marginal emotional or instrumental support, lack of social engagement). RESULTS: Living alone status was more strongly associated with marginal instrumental support [OR=7.6 (95% CI 6.3, 9.1)] than with marginal emotional support [OR=4.2 (95% CI 3.4, 5.1)], and showed no statistically significant association with lack of social engagement [OR=0.9 (95% CI 0.8, 1.0)]. Risk of social isolation was more strongly related to marginal emotional support [OR=6.6 (95% CI 5.4, 8.0)] than to marginal instrumental support [OR=3.3 (95% CI 2.8, 4.0)], and was moderately related to lack of social engagement [OR=2.9 (95% CI 2.5, 3.4]. Marginal family and friend network subscales showed consistent and unique associations with social support and social engagement. CONCLUSION: Findings suggest that living alone status and a brief measure of social network identifies distinctive at-risk groups and potential pathways for intervention. Geriatric assessment programs including both social network measures may provide useful information about potentially modifiable social network risks in older persons.