This article examines individual and social factors associated with initiation of illicit drug injection, with a focus on racial differences. Data were derived from across-sectional survey of young injection and noninjection drug users in Baltimore, Maryland. Participants were aged 15 to 30 and had initiated use of heroin, cocaine, and/or crack within the prior five years. Bivariate and multivariate logistic regression models were used to identify correlates of injection initiation. Of 579 drug users, 73% were injectors, 56% were male, and 41% were African American. In a multivariate model controlling for age, correlates of injection initiation were: being an African American male [Adjusted Odds Ratio (AOR): 0.08; 95% Confidence Interval (CI): 0.04, 0.17] or female (AOR = 0.12; 95%CI: 0.06, 0.27) compared to being a White male; younger age of first use of alcohol, marijuana, or inhalants (AOR=0.73; 95%CI: 0.65, 0.82); shorter time between first use of alcohol, marijuana, or inhalants and first use of heroin, crack, or cocaine (per year decrease, AOR=0.63, 95%CI: 0.40, 0.87); parental drug use (AOR=0.54, 95%CI: 0.32, 0.92); seeing someone inject prior to injection, AOR=1.96, 95%CI: 1.01, 3.50); and crack smoking (AOR=1.77, 95%CI: 1.07, 2.99). Early drug use patterns and drug exposure factors are associated with initiation injection. Interventions are needed that target noninjection drug users to prevent transition to injection drug use.