Purpose: Differences in social cognition between autistic and non-autistic people may put autistic people at greater risk of being deceived. To inform communication interventions related to deception, the purposes of this mixed-methods study were to examine the deception detection strategies used by young adults with varying levels of autistic traits and to explore whether those strategies differed between groups or in terms of accuracy. Methods: Fifty-one young adults with varying levels of autistic traits watched a series of videos. For each video, the participant judged whether the recorded speaker was truthful and gave the reasoning for their judgment. Inductive thematic analysis was used to identify themes in participants' stated reasons, which were used to quantitatively examine: (1) between-group differences based on self-reported autistic traits and (2) theme-based differences in accuracy. Results: Thematic analysis of the open-ended responses yielded four major themes: subjective descriptions of the person, nonverbal communication, observable features of the response, and nebulous reasons. Statistical analyses indicated no significant group differences in frequency of use of the four themes. When the four themes were compared with each other, observable response features yielded significantly more accurate judgments than nonverbal communication or subjective descriptions. Discussion: Findings are discussed within the framework of speech-language pathologists' role in helping communicators determine a speaker's truthfulness, with the ultimate goal of avoiding deception and/or manipulation. Suggestions for incorporating research findings into the design of communication interventions are included.