The research literature has repeatedly emphasized the importance of parent involvement and parent training in the early intervention of young children with autism spectrum disorder (ASD). In fact, parent mediated Early Intensive Behavioral Intervention (EIBI) programs have become a popular method of treatment in recent years. Studies examining these programs have demonstrated that a number of variables may significantly impact the outcomes of EIBI. Moreover, an examination of the psychotherapy literature underscores the importance of a strong parent-therapist alliance as a correlate of positive processes and outcomes in child therapy; while there is very little research examining the working alliance as a factor in parent consultation. The purpose of the present study was to examine the relationship between the working alliance and the consultation process in parent-mediated EIBI for young children with ASD. Forty-four parents of children with an ASD, who were also conducting home-based EIBI programs, completed the Working Alliance Inventory (WAI) (Horvath & Greenberg, 1989) plus other measures that assessed treatment process and outcome. In addition, eight independent consultants completed similar measures to assess perceptions of alliance, process, and outcomes of their consultees. The results showed parent ratings of the working alliance were significantly correlated with parent ratings of treatment acceptability for child treatment as well as for parent consultation. Parent ratings of alliance also correlated significantly with parent ratings of parent progress in consultation and child progress in treatment. Consultant ratings of alliance were significantly correlated with both parent progress and parent improvement in consultation. This suggests that the working alliance may be a contributing factor to the process and outcome of consultation with parents of children with ASD. The results of the present study were compared to the current literature on the therapeutic alliance and relationship factors in consultation. The limitations of the present study and suggestions for future research are also discussed.