Introduction: The family, as the primary and most fundamental social institution, plays a pivotal role in shaping personality development and fostering the emotional and social growth of children. Among family members, parents—particularly mothers—create a secure and accepting environment that facilitates healthy psychological development in their offspring.

Objective: The present study aimed to determine the effectiveness of Acceptance and Commitment Therapy (ACT) on communication patterns of mothers with children diagnosed with Separation Anxiety Disorder.

Method: The research design was quasi-experimental with a pretest-posttest control group design, including a two-month follow-up period. The statistical population comprised mothers with children diagnosed with separation anxiety who were referred to counseling centers in Isfahan during the 2024-2025 academic year. A sample of 30 mothers with children diagnosed with separation anxiety was selected using purposive sampling method and randomly assigned to experimental and control groups. The data collection instrument utilized in this study was the Child-Parent Relationship Scale (CPRS) developed by Pianta (1992). The ACT therapeutic intervention was administered to the experimental group in eight weekly 60-minute group sessions. The collected data were analyzed using Analysis of Covariance (ANCOVA) statistical method and SPSS software version 24.

Findings: The results demonstrated a significant group effect, indicating meaningful differences between the intervention and control groups in mean scores across all three communication patterns throughout all study phases (P < 0.05).

Conclusion: The emphasis of Acceptance and Commitment Therapy on committed and purposeful action enables mothers to shape their communicative behaviors based on long-term objectives and personal values rather