In the 21st century, we have seen a significant increase in the use of alcohol and other drugs (AODs) among older adults in most first world countries. In addition, people are living longer. Consequently, the number of older adults at risk of experiencing alcohol-related harm and substance use disorders (SUDs) is rising. Between 1992 and 2010, men in the United Kingdom aged 65 years or older had increased their drinking from an average 77.6 grams to 97.6 grams per week. Data from Australia show a 17% increase in risky drinking among those 60–69 between 2007 and 2016. Among Australians aged 60 or older, there was a 280% increase in recent cannabis use from 2001 to 2016. In the United States, rates of older people seeking treatment for cocaine, heroin, and methamphetamine have doubled in the past 10 years. This trend is expected to continue. Despite these alarming statistics, this population has been deemed “hidden,” as older adults often do not present to treatment with the SUD as a primary concern, and many healthcare professionals do not adequately screen for AOD use. With age, changes in physiology impact the way we metabolize alcohol and increase the subjective effects of alcohol. In addition, older adults are prone to increased use of medications and medical comorbidities. As such, drinking patterns that previously would have not been considered hazardous can become dangerous without any increase in alcohol consumption. This highlights the need for age-specific screening of all older patients within all healthcare settings. The etiology of AOD-related issues among older adults can be different from that of younger adults. For example, as a result of issues more common as one ages (e.g., loss and grief, identity crisis, and boredom), there is a distinct cohort of older adults who develop SUDs later in life despite no history of previous problematic AOD use. For some older adults who might have experimented with drugs in their youth, these age-specific issues precipitate the onset of a SUD. Meanwhile, there is a larger cohort of older adults with an extensive history of SUDs. Consequently, assessments need to be tailored to explore the issues that are unique to older adults who use AODs and can inform the development of age-specific formulations and treatment plans. In doing so, individualized treatments can be delivered to meet the needs of older adults. Such treatments must be tailored to address issues associated with aging (e.g., reduced mobility) and may require multidisciplinary input from medical practitioners and occupational therapists.