The need to fully understand the possible consequences of young-adult cannabis use has become increasingly critical as a result of major cannabis policy changes. The purpose of this study was to determine if young-adult users exhibit cognitive deficits on laboratory-based tests and memory and attention deficits in everyday life. Participants were 152 students from a large U.S. university enrolled in introductory psychology courses and the top and bottom 10% of the 12-item Yale University PRIME Screening Test for psychotic-like experiences. Participants were asked about their cannabis use and were given six cognitive tests spanning executive function and memory. To test functional impairment in memory and attention, participants were asked to nominate informants (people who knew them well) and these rated the participants on an attention problems scale of four items and a memory problems scale of three items. Results showed that individuals who used cannabis more frequently were rated as having more attention and memory problems and that, consistent with prior research, more frequent cannabis use was associated with worse memory test performance, though the association was not present between frequency of use and executive function test performance. Additionally, it was found that informant-reported attention problems were associated with poorer performance on two of the executive function cognitive tests. The present findings suggest that individuals who use cannabis more frequently experience noticeable memory and attention problems in everyday life, despite the lack of significant correlation between this functional impairment and cognitive test performance. Informant reports, therefore, may be useful in future research for understanding or predicting cognitive impairment in young adults.