The aim of the present study was to predict marital adjustment based on couples' attachment styles, with the mediating role of communication patterns. The research method was descriptive-correlational, using structural equation modeling. The statistical population consisted of all married couples in Tehran in 2023. A total of 514 married individuals were selected using convenience sampling, drawn from students of Payame Noor University of Tehran (District 3), parents of students in schools and educational centers in Tehran (District 6), clients and instructors of the Institute for the Intellectual Development of Children and Young Adults in Tehran (District 6), and clients of cultural centers and the Cultural-Social Deputy of Tehran (Districts 2 and 22). Data were collected using the Dyadic Adjustment Scale (Spanier, 1976), the Adult Attachment Inventory (Hazan & Shaver, 1987), and the Communication Patterns Questionnaire (Christensen & Sullaway, 1984), and analyzed using Pearson's correlation coefficient (SPSS version 27) and structural equation modeling (AMOS version 25). The findings showed that the research model had a favorable fit. There was a significant positive relationship between communication patterns and attachment styles with marital adjustment (P<0.01). The path coefficient between attachment styles and communication patterns with marital adjustment was also positive and significant (P< 0.01), and attachment styles indirectly affected marital adjustment through their effect on communication patterns (P < 0.01). It can therefore be concluded that couples' attachment styles affect marital adjustment among couples in Tehran through their effect on communication patterns.