Background Individuals with intellectual disability (ID) are more vulnerable to abuse compared to individuals without disabilities yet have limited access to the legal system. This study examined perceived credibility of youth with mild intellectual disability (MID) who provide courtroom testimony. Method Participants, 187 undergraduates, were asked general questions about credibility. They also read eyewitness testimony and answered questions about a particular witness's credibility. Half the participants were informed that the youth has MID chronological age (CA) 15 years, mental age (MA) 10 years and the others were informed that the youth is a typically developing 10-year-old. Results When participants were asked general questions about credibility they rated 15-year-olds with MID (MA 10years) as less credible than typically developing 15-year-olds and as less credible than typically developing 10-year-olds. However, when participants read eyewitness testimony and answered questions about a particular witness's credibility, no statistically significant differences were found between participants who were informed that the witness was a 15-year-old with MID (MA 10years) and those who were informed that the witness was a typically developing 10-year-old. Conclusions The present study provided a preliminary investigation of perceived credibility of witnesses with MID and suggests directions for future research in this area.