Abstract: Objective: Attachment style and social support networks (SSN) are associated with suicide ideation (SI) and suicide attempt (SA). How these two factors interact is important to understanding the mechanisms of risk for suicidal behaviors and identifying interventions. Method: Using the Army Study to Assess Risk and Resilience in Servicemembers New Soldier Study (N = 38,507 soldiers), we examined how three attachment styles (preoccupied, fearful, and secure) and SSN (smaller vs larger) were associated with lifetime SI, SA, and SA among soldiers with SI. The interaction of each attachment style by SSN was examined. Results: All three attachment styles were associated with SI and SA in the total sample (for SA: preoccupied OR = 2.82, fearful OR = 2.84, and secure OR = 0.76). Preoccupied and fearful attachment were associated with SA among suicide ideators. Smaller SSN was associated with a higher risk for all three outcomes (range of ORs = 1.23–1.52). The association of SSN with SI and with SA among suicide ideators was significantly modified by the presence or absence of preoccupied attachment style. Among soldiers without preoccupied attachment, larger SSN was associated with lower risk of SI. Among suicide ideators with preoccupied attachment, a larger SSN was associated with lower risk of SA. Conclusion: This study highlights the need for increased understanding of the role of attachment style and social networks in suicide risk, in particular preoccupied attachment among soldiers with SI. A critical next step is to explore these relationships prospectively to guide intervention development.