Developmental approaches to autism treatment aim to establish strong interpersonal relationships through joint play. These approaches have emerging empirical support; however, there is a need for further research documenting the procedures and demonstrating their effectiveness. This pilot study evaluated changes in parent behavior and child autism symptoms following a 12-week Developmental Reciprocity Treatment parent-training program. A total of 22 children with autism spectrum disorder between 2 and 6 years (mean age = 44.6 months, standard deviation = 12.7) and a primary caregiver participated in 12 weekly sessions of Developmental Reciprocity Treatment parent training, covering topics including introduction to developmental approaches, supporting attention and motivation, sensory regulation and sensory-social routines, imitation/building nonverbal communication, functional language development, and turn taking. Results indicated improvement in aspects of parent empowerment and social quality of life. Improvement in core autism symptoms was observed on the Social Responsiveness Scale total score (F(1,19): 5.550, p = 0.029), MacArthur-Bates Communicative Development Inventories number of words produced out of 680 (F(1,18): 18.104, p = 0.000), and two subscales of the Repetitive Behavior Scale, Revised (compulsive, p = 0.046 and restricted, p = 0.025). No differences in sensory sensitivity were observed on the Short Sensory Profile. Findings from this pilot study indicate that Developmental Reciprocity Treatment shows promise and suggest the need for future controlled trials of this developmentally based intervention.