Dual-striplines are gaining popularity in the high-density computer system designs to save printed circuit board (PCB) cost and achieve smaller form factor. However, broad-side near-end/far-end crosstalk (NEXT/FEXT) between dualstriplines is a major concern that potentially has a significant impact to the signal integrity. In this paper, the broadside coupling between two differential pairs, and a differential pair and a single-ended trace in a dual-stripline design, is investigated and characterized. An innovative design methodology and routing strategy are proposed to effectively mitigate the broad-side coupling without additional routing space.