SAN FRANCISCO — Continuing its skillful ride on the mobile computing wave, Facebook on Wednesday posted strong growth in revenue and profits for the second quarter.

The social networking company, which said it had about 1.32 billion monthly users in June, reported that revenue was $2.91 billion, up 61 percent from $1.81 billion during the same period last year. Net income was $791 million, or 30 cents a share, compared to $333 million, or 13 cents a share, a year ago. The company’s operating profit margin hit a record 48 percent in the second quarter, reflecting increased cost efficiencies.

Mobile devices accounted for nearly two-thirds of the company’s revenue, which mostly comes from ads shown on the Facebook website and apps.

Analysts had expected Facebook, based in Menlo Park, California, to report revenue of $2.8 billion.

Wall Street had also projected that the company would post a profit of 32 cents a share, after excluding compensation-related expenses, according to consensus estimates collected by several services.

This year, eMarketer predicts, Facebook will garner nearly 8 percent of the world’s digital ad revenue and 22.3 percent of mobile ad revenue, which the firm projects will nearly double globally as people turn increasingly to phones as their primary on-ramp to the Internet.