Centromeres and heterochromatin play significant roles in gene expression regulation. We hypothesize that DDX18, a protein that localizes in the nucleolus, may play a role anchoring centromeres to the nucleolus and organizing perinucleolar heterochromatin. Investigating its role in these processes would allow us to better understand the mechanism and purpose behind the centromere-nucleolus and heterochromatin-nucleolar associations, and broader implications for gene expression regulation in malignant cells. HeLa cells were transfected siRNA against DDX18 mRNA to reduce its expression. Immunofluorescence was then used on DDX18 knockdown and control cells to evaluate centromere association with nucleoli, Pol I transcription machinery, and heterochromatin organization. A Nikon Eclipse Ti microscope was used with Elements software to image and quantify the results of immunofluorescence. Two sample t-tests were used to verify significance. Knocking down the expression of DDX18 gene in HeLa cells did not significantly affect Pol I transcription machinery or nucleolar structure. However, the knockdown caused a significant decrease in heterochromatin clusters around nucleoli and centromere-nucleoli association compared to the control (p < 0.05), supporting the hypothesis that DDX18 plays a role in anchoring centromere and heterochromatin to the nucleolus. In the future, we seek to investigate the mechanisms by which DDX18 regulates the nucleolar association with centromere and heterochromatin, and their role in cancer cells.