According to 2020 statistics from NIDA, the lifetime prevalence of illicit substance use disorder (SUD) in eighth graders is 21.3%, which increases up to 46.6% in 12th graders. SUD is the second most common mental health complaint in children to the emergency room (ER). The ER can be used as a screening site for prevalence of this disorder. We conducted a CRAFFT (Car, Relax, Alone, Forget, Friends, Trouble) survey to determine the prevalence of SUD in children and adolescents with mental health disorders (CA-MHD). A cross-sectional quality improvement (QI) study was done on children presenting to the Child and Adolescent Psychiatric ER of South Bronx, NY with mental health complaints, between April and June 2021. Participants were screened for concomitant substance use disorder with the CRAFFT questionnaire and a structured survey to observe reasons for using a substance, effects on mood and functionality, and help/treatment received for substance use. Our data comprised 151 patients (61 males and 90 females) with 63 children (42%) and 88 adolescents (58%) presented. With respect to ethnicity, 89 were Hispanics (59%), 57 were African Americans (38%), and 4 were other ethnicities (3%). Forty-two participants (28%) endorsed substance use. Marijuana was the most commonly used substance (29 patients), followed by alcohol (10), and other illicit substances (3). Eight participants denied the use of marijuana, but their urine drug screen was positive for cannabinoids. Patients using drugs were asked about seeking help in the past for substance issues; however, all reported they have not taken any help nor do they want to take any help in the future. Commonly identified reasons for substance use in descending order are frustration due to personal issues, loneliness, and feeling sad. Participants reported that substance use helped them in remaining calm amid work and forgetting about the problems. SUD is prevalent among CA-MHD presenting to the ER, with cannabis being the most used substance in this age group. The majority of substance users identified interpersonal problems to be the trigger for substance use; hence, interpersonal therapy can be useful in ameliorating this pattern. More studies are required to delineate the exact efficacy. Presently, this study is still ongoing, and in the future, we will have more comprehensive and bigger data sets.