This study investigated family dynamics and substance use disorders among the youth in selected rehabilitation centers in Nairobi County, Kenya. Using Yamane (1967) formula, a sample of 172 clients was obtained and selected randomly to take part in quantitative study. Another 12 clients who had stayed in rehabilitation centers for the longest time were purposively selected in order to provide qualitative data. Similarly, 10 parents were conveniently selected in order to provide qualitative data. Therefore the total sample size comprised of 196 respondents. Quantitative data was collected using FACES-IV, AUDIT, and DAST-10 questionnaires while qualitative data was collected using interview guides. Cronbach Alpha technique was run to test the reliability of FACES-IV, AUDIT, and DAST-10. FACES-IV scale was found to have a reliability coefficient of .723, AUDIT had reliability of .861while DAST-10 scale had a reliability coefficient of .812. Quantitative Data analysis was done using descriptive statistics and inferential statistics while qualitative data was analysed thematically backed by narratives from respondents. The study had the following findings, most respondents came from families with unhealthy cohesion (disengaged family cohesion (Mean= 25.4545; SD= 9.3575), there was a strong negative and significant correlation between disengaged family cohesion and drug use disorder (r=-0.527; P= 0.000).