D&C Other revenue increased $235 million or 17%, due mainly to higher advertising revenue, which increased $106 million or 13%. Search advertising revenue growth was offset in part by a decline in display advertising revenue. Search advertising revenue increased 47%, due primarily to increased revenue per search resulting from ongoing improvements in ad products and higher search volume, offset in part by lower display advertising revenue, which was down 31%, due mainly to a decline in Outlook.com advertising revenue. D&C Other revenue also increased $129 million or 21%, primarily due to higher volumes of content resold through our online platforms.
D&C Other gross margin decreased slightly, due to a $245 million or 24% increase in cost of revenue, substantially offset by higher revenue. D&C Other cost of revenue increased, due mainly to a $99 million or 20% increase in advertising cost of revenue, reflecting increased investment in online infrastructure and higher traffic acquisition costs. D&C Other cost of revenue also increased, due mainly to royalty costs on higher volumes of resale transactions.