Arsole-containing conjugated polymers are a practically unexplored class of materials despite the high interest in their phosphole analogues. Herein we report the synthesis of the first dithieno[3,2-b;2′,3′-d]arsole derivative, and demonstrate that it is stable to ambient oxidation in its +3 oxidation state. A soluble copolymer is obtained by a palladium-catalyzed Stille polymerization and demonstrated to be a p-type semiconductor with promising hole mobility, which was evaluated by field-effect transistor measurements.