Study aim: Effectiveness of Acceptance and Commitment-based Therapy (ACT) on Experiential Avoidance, Intolerance of Uncertainty and Meta-parenting among Mothers of Children with Autism Spectrum Disorder Design: a quasi-experimental, pretest–posttest design with two parallel groups (experimental and control), single-blind procedure and randomization based on a random number table, 30 participants, two-month follow-up period Settings and conduct: This study will be conducted at the “Darya” Autism Rehabilitation Center in Behbahan, under the supervision of the Welfare Organization. After screening participants based on the inclusion and exclusion criteria and obtaining informed consent, they will be randomly assigned to either the experimental or control group. The intervention will be implemented at the center, and data will be collected from both groups through pre-test and post-test assessments using questionnaires. Participants/Inclusion and exclusion criteria: Inclusion criteria: Being mother of a child with autism, Being in the age range of 25 to 45 years, Not suffering from specific psychiatric disorders or physical diseases that require the use of drugs or special treatment, Not being divorced or head of household. exclusion criteria: Participating in other therapy sessions at the same time, suffering from physical diseases or psychiatric disorder in a way that interferes with treatment sessions or requires hospitalization or drug therapy, Reluctance to continue cooperation Intervention groups: Following random assignment, the experimental group will received group-based Acceptance and Commitment Therapy (ACT) across 8 to 10 ninety-minute sessions, while the control group will received no intervention. A pretest-posttest design will employed to evaluate both groups. Main outcome variables: Experiential avoidance, Intolerance of uncertainty, Meta-parenting