Spouses of National Guard/Reserve (NG/R) military service members cope with deployment-related stressors (DRS) that may contribute to increased psychological distress. Research indicates that higher levels of social support are associated with reduced depression and anxiety in military spouses, but longitudinal relationships have not yet been examined bidirectionally. This study examines temporal relationships between 3 dimensions of social support (social connectedness, dyadic satisfaction, and perceived support), and psychological distress in a sample of NG/R spouses during the first year after a service member returns from deployment. Data from 103 military spouses were drawn from a larger intervention development study. Autoregressive cross-lagged panel analyses examined the stress-buffering and support erosion hypotheses over a 3-month period. DRS were measured by the cumulative number of deployments and duration of most recent deployment. Distress was assessed using latent variables of depression and anxiety. Statistically significant relationships emerged between initial levels of psychological distress and social connectedness at 3 months. Social support dimensions of dyadic satisfaction and perceived support did not predict subsequent levels of psychological distress. No significant relationships emerged between any dimension of social support at baseline and either form of psychological distress at 3 months. The support erosion hypothesis may more accurately describe the relationship between social support and psychological distress in this sample than the stress-buffering mechanism. During the first year of reintegration, social connectedness may be of particular relevance for NG/R spouses, as they may not have access to supports typically available to their active duty counterparts. Public Policy Relevance Statement Reintegration can be a stressful time for military families. Social support is essential for maintaining good psychological and physical health, especially during times of stress. This study explores two causal models of the relationship between three unique dimensions of social support and psychological distress in National Guard/Reserve (NG/R) military spouses during reintegration. Findings indicate that the support erosion hypothesis, wherein higher levels of psychological distress predict subsequent reductions in social connectedness, best explains this relationship in military spouses during the first year of reintegration. Findings suggest the need for development of additional community-based supports for NG/R spouses, as they may not have access to supports typically available to their active duty counterparts.