CANTON, MASS. — Strong comparable store sales and net unit development contributed to a 121% increase in income for Dunkin’ Brands Group, Inc. during the second quarter.

For the quarter ended June 29, the company posted net income of $40.8 million, equal to 38c per share on the common stock, up from $18.5 million, or 15c per share, during the same period of the previous year. A 67% increase in operating income contributed $30.7 million, offset by a $4.4 million rise in income tax expense and a $3.2 million increase in interest expense.

Total revenues were $182.5 million during the quarter, up 6% from $172.4 million during the same period of the previous year.

“Innovative marketing and new product introductions, as well as a focus on delivering a great customer experience, continue to deliver attractive franchisee returns and exceptional results for Dunkin’ Donuts in the U.S.,” said Nigel Travis, chairman and chief executive officer. “Additionally, we continue to see significant interest in restaurant development for Dunkin’ Donuts in this country, and for the second consecutive quarter, Baskin-Robbins U.S. experienced positive net growth. On the international front, we continue to build the foundation for the long-term growth of both brands.”

During the quarter, the company added 151 net new restaurants worldwide, including 63 Dunkin’ Donuts locations in the United States.

Increased average ticket and higher traffic drove Dunkin’ Donuts U.S. to a 4% growth in comparable sales, led by cold beverage introductions, including iced coffee flavors inspired by Baskin-Robbins ice cream and new Coolatta flavors, continued momentum in breakfast sandwiches, growth in new afternoon offerings and increased donut sales from a National Donut Day program in June.

At Baskin-Robbins U.S. stores, Flavors of the Month and cakes for Mother’s Day, Father’s Day and graduation season contributed to a nearly 2% growth in comparable store sales.

“Going into the second half of the year, we are confident about our business prospects and are steadfastly focused on delivering profitable growth for our franchisees and shareholders,” Mr. Travis said.