The hypothesis that attachment insecurity would be associated with remaining in an unhappy marriage was tested. One hundred seventy-two newly married couples participated in a 4-year longitudinal study with multiple assessment points. Hierarchical linear models revealed that compared with spouses in happy marriages and divorced spouses, spouses who were in stable but unhappy marriages showed the highest levels of insecurity initially and over time. Spouses in stable, unhappy marriages also had lower levels of marital satisfaction than divorced spouses and showed relatively high levels of depressive symptoms initially and over time. Results suggest that spouses at risk for stable, unhappy marriages can be identified early and may benefit from interventions that increase the security of spouses' attachment to each other.