Social networks and social support can influence older adults' depressive symptoms, but depressive symptoms can also influence network maintenance. This study examined longitudinal relationships between social network structure, social support, and depressive symptoms.Data are from Waves 1 (2005-2006) and 2 (2010-2011) of the National Social Life, Health, and Aging Project, a longitudinal study on health and social factors of older adults. Models examining: (i) the influence of T1 network structure and T1 social support on T2 depressive symptoms; (ii) the influence of T1 depressive symptoms and T1 network structure on T2 social support; and (iii) the influence of T1 depressive symptoms and T1 social support on T2 network structure, were estimated using ordinary least squares lagged dependent variable regression models.Evidence of reciprocal associations between social support and depressive symptoms were found, as well as social support and the number of close ties and frequency of contact. No clear reciprocal associations between social network structure and depressive symptoms were found, although density was associated with later depressive symptoms, and depressive symptoms were associated with later number of close ties.The reciprocal relationship between network structure and depressive symptoms is weak, whereas social support is strongly related to both depression and network structure, suggesting the importance of having supportive ties in an older adult's personal network for positive mental health.