Individuals with autism spectrum disorders (ASD) have notable language difficulties, including with understanding narratives. However, most narrative comprehension studies have used written or spoken narratives, making it unclear whether narrative difficulties stem from language impairments or more global impairments in the kinds of general cognitive processes (such as understanding meaning and structural sequencing) that are involved in narrative comprehension. Using event-related potentials (ERPs), we directly compared semantic comprehension of linguistic narratives (short sentences) and visual narratives (comic panels) in adults with ASD and typically-developing (TD) adults. Compared to the TD group, the ASD group showed reduced N400 effects for both linguistic and visual narratives, suggesting comprehension impairments for both types of narratives and thereby implicating a more domain-general impairment. Based on these results, we propose that individuals with ASD use a more bottom-up style of processing during narrative comprehension.