Although smoking rates have declined in most of the countries in the world, there are population groups within these countries whose smoking rates remain significantly higher than the general population. These “forgotten groups” who have not been receiving the needed attention in tobacco control policies and tobacco cessation efforts include people with serious mental illness, substance use disorders, tuberculosis, people living with human immunodeficiency virus (HIV), lesbian-gay-bisexual-transgender-queer people, and pregnant women. A number of steps are needed at the national level in countries where these disparities exist, including modifications to national smoking cessation treatment guidelines that address the special needs of these populations, as well as targeted smoking cessation research, since these populations are often not included in clinical trials. Because of the higher smoking prevalence in these populations, as well as their lower smoking cessation treatment success rates than the general population, more resources are needed if we are to reduce health disparities in these vulnerable populations. Additionally, we believe that more effort should be focused on integrating smoking cessation treatment in the specialized care settings frequented by these subpopulations.