Promoter-proximal pausing of RNA Polymerase II (PolII) is a widespread transcriptional regulatory mechanism. DSIF and NELF contribute to pausing by binding to PolII, and DSIF recruits NELF to the PolII elongation complex. To understand how DSIF recruits NELF, I generated DSIF mutants based on available structural data and will test the ability of these mutants to bind PolII and recruit NELF. This study will provide mechanistic insight into regulation of promoter-proximal pausing by transcription factors.