Background This study investigates the association between inhalant use and executive cognitive functioning (ECF) and processing speed (PS) in 754 adjudicated poly‐substance users on a series of neuropsychological tests. Poly‐substance users who used inhalants (PSI = 262) and poly‐substance users who did not use inhalants (PSO = 492) neuropsychological tests scores were compared. Hispanic Americans comprised 72% of the participants; European Americans, African Americans and Asian Americans comprised 28% of the participants. Methods Standardized neuropsychological tests were used to assess ECF and PS. Psychosocial and substance abuse standardized surveys were used to assess drug use severity and psychosocial problems associated with substance use. Results Multiple Analysis of Covariance shows that PSI users who used inhalants performed worse on ECF and PS measures in comparison to non‐inhalant poly‐substance users (PSO). PSI users were younger, used more drugs and had more psychiatric admissions than PSO users. Conclusion PSI users initiate substances at a younger age and experienced more ECF and PS deficits, and behavioural problems in comparison to PSO users. The results of this study suggest that PS has direct effect on ECF and psychosocial outcomes in PSI users.