Few studies report prevalence rates of alcohol and cannabis use among 2-year college students, and the prevalence rates that are reported are not derived from national samples (e.g., Cadigan et al., 2019; Wall et al., 2012). Compared to national estimates from MTF (Patrick et al., 2024), a smaller proportion of 2-year students in our screening sample reported past-month alcohol use (52.9%) compared to 2- and 4-year college students in MTF (62.5%), but prevalence of HED was slightly higher in our sample (33.1% in our sample; 27.7% in MTF). For cannabis use, more students in our screening sample reported past-month cannabis use (36.2%) compared to 2- and 4-year students in the MTF study (22.1%). Recent work (Cadigan et al., 2019; Duckworth et al., 2024) suggests that 2-year students may be at increased risk for cannabis use relative to 4-year students. However, these samples were drawn from Washington State, where nonmedical cannabis use is legal for adults over the age of 21, which may confound findings. For instance, a recent study found that cannabis use among female 2-year college students who use alcohol had differential findings for those living in states without non-medical cannabis legalization (Binger et al., 2023). More research is needed to understand differences in cannabis use among 2-year college students living in states with different cannabis use legislation.

Consistent with prior research examining descriptive peer norms among 4-year college students (e.g., Baer et al., 1991; Borsari & Carey, 2003; Kilmer et al., 2006), students in the follow-up sample (i.e., students who reported recent, moderate use) overestimated how much other 2-year students of the same gender drank alcohol, engaged in HED, and used cannabis. For example, screening sample participants reported drinking three drinks and being high for 8 h per week on average, whereas follow-up participants perceived that their peers were drinking ten drinks and were high for 13 h per week on average. As hypothesized, results also indicated overestimations were positively related to personal use and consequences. Specifically, for descriptive norms, higher perceived peer alcohol use was related to greater personal drinking and HED, and higher perceived peer cannabis use was related to greater personal cannabis use. Findings are consistent with Social Norms Theory (Berkowitz, 2004) and suggest that interventions aimed at decreasing misperceptions of peer alcohol and cannabis use may be effective in decreasing personal use.

For injunctive norms, higher perceived peer approval of alcohol use was related to more personal alcohol-related consequences, while perceived peer approval of cannabis use was unrelated to personal use or consequences. The finding that perceived injunctive norms were not related to personal alcohol or cannabis use was contrary to our hypotheses and is inconsistent with Social Norms Theory (Berkowitz, 2004). However, this finding is consistent with prior research among 4-year student samples that descriptive norms tend to be more strongly associated with substance use behaviors than injunctive norms (Borsari & Carey, 2003; Zou & Savani, 2019), suggesting that young adults’ perceptions of their peers’ behaviors may influence their own actions more than their perceptions of their peers’ attitudes. Additionally, the finding that injunctive norms were related to alcohol-related consequences but not cannabis-related consequences may stem from how injunctive norms were assessed: participants evaluated perceived peer approval of high-risk alcohol behaviors (e.g., daily drinking and driving after drinking) but lower-risk cannabis behaviors (e.g., trying cannabis once or twice and using cannabis occasionally). Findings for injunctive alcohol norms may be due to the long-standing cultural normalization of alcohol in social settings, particularly among young adults. Alcohol use is often portrayed as a typical part of college life, making peer attitudes more influential in shaping individual behaviors (Borsari & Carey, 2001). The social nature of drinking, coupled with its integration into social activities, may heighten the impact of peer norms in encouraging alcohol use (Neighbors et al., 2007). In contrast, cannabis use, though legal in Washington State, may not exhibit the same degree of peer influence. Cannabis use can still carry some stigma or may be viewed as more private and individualized compared to alcohol. Factors such as medical use or personal coping strategies might play a larger role in cannabis consumption, making it less dependent on peer approval (Kilmer et al., 2006).

Contrary to Social Comparison Theory (Festinger, 1954) and Social Impact Theory (Latané, 1981) and inconsistent with prior research of 4-year students and alcohol use (e.g., Reed et al., 2007), identification with the reference group did not moderate associations between perceived peer norms and personal use and consequences. Social Comparison Theory (Festinger, 1954) and Social Impact Theory (Latané, 1981) suggest that more proximal reference groups exert a stronger influence than more distal reference groups. Research with 4-year college students supports this notion, demonstrating that interventions are generally more effective when individuals feel a stronger connection to the reference group (Neighbors et al., 2010; Reed et al., 2007). Given that 2-year students are a much more diverse group than 4-year students (Snyder et al., 2019; Velazquez et al., 2011), it may be that the typical same-gender community college student is not the best reference group for 2-year college students. Indeed, follow-up participants in this study only somewhat identified with the typical same-gender community college students. Future research could explore if other reference groups are more salient for community college students, such as typical same-gender, same-age young adults.

Finally, student age did moderate associations between perceived peer norms and personal use and consequences, which was an exploratory research question. For alcohol use, associations between perceived peer drinks per week (descriptive norms) and personal drinks per week were less pronounced for older students relative to students aged 21–25, as were associations between greater perceived peer approval of alcohol use (injunctive norms) and personal alcohol-related consequences. These findings are not surprising given developmental, social, and contextual differences between young adults in their late 20s and young adults in their early-to-mid 20s. For instance, according to Erikson’s Psychosocial Theory of Development, younger students are often still in the late adolescence stage of development and may be more susceptible to peer influence as they navigate the Identity vs. Role Confusion stage, where social approval and experimentation with roles are central (Orenstein & Lewis, 2022). In contrast, older students are often transitioning into Erikson’s Intimacy vs. Isolation stage and may be less focused on peer approval and more influenced by life roles, such as work, relationships, and future aspirations (Orenstein & Lewis, 2022). Older students are also more likely to have a realistic understanding of peer behavior, weakening the influence of exaggerated perceptions of drinking norms (Staff et al., 2010). Our findings, coupled with this developmental trajectory, underscore the fact that interventions addressing perceived norms may be most effective for younger college students.