All individuals are at some risk of developing an addiction. This includes individuals who utilize prescription drugs and those that use drugs recreationally. The reasons why individuals use substances is complex. Broad social, economic and environmental factors influence why someone initially and continues to use drugs. These factors are called the social determinants of health. Education, employment/poor working conditions and housing, social environment (e.g., safe neighborhood, family violence), access to social support networks and health services; and personal factors such as gender, personal skills (e.g., resiliency), ethnic background and biology/genetics all play a role in substance use and addictions. These determinants of health can be protective factors against substance use and they can also be risk factors to substance use and addiction. It is important to remember that, while the social determinants of health may contribute to addiction and substance use, there is no single set of factors that represents the complex causes of addiction. Harm reduction services recognize that not all individuals are ready or willing to give up substance and help reduce harm/exposure of individuals who are using substances to infectious disease.