Special populations refers to groups of individuals who have unique characteristics or needs that require specific attention and consideration in research. This can include marginalized or vulnerable populations such as ethnic minorities, individuals with disabilities, LGBTQ+ individuals, homeless individuals, and individuals experiencing poverty or other forms of social disadvantage. Researchers working with special populations must take into account the unique challenges and barriers these individuals may face in participating in research, and they must also ensure that ethical guidelines and considerations are being met in working with these groups. Overall, research with special populations aims to increase understanding and address the needs of these unique groups, ultimately contributing to more inclusive and equitable research practices.