Under the terms of the cash and stock deal, Alloy issued 1.7 million shares of stock, worth about $23.8 million--based on Friday's closing price of $13.99--and $9.7 million in cash.
Alloy stock was up 8 percent to $14.61 in midday trading Tuesday.
New York-based Alloy has gone on a buying spree this year. In May, the company acquired Carnegie Communications, which provides information about college applications to high-school students through various publications and Web sites.
Alloy is pushing forward with its strategy of selling goods and marketing to young adults through a combination of offline and online channels. The company was among the first Internet-only companies to adopt an offline strategy and operates a direct mail catalog, magazines, books and college guides as well as Web sites.
"Cass significantly increases our reach into the teen and young adult demographic groups," said Matt Diamond, Alloy's chief executive.
Based in Evanston, Ill., Cass reaches more than 21 million readers, according to Alloy. The company's outdoor billboards and displays also reach another 6.5 million students on college and high-school campuses.
One of the few teen sites to survive the dot-com shakeout, Alloy has a range of teen-focused content and e-commerce. The company, which topped earnings for the first quarter, hosts chat rooms, posts articles, and sells clothes, furniture and sports equipment.
Alloy posted a net loss of $10.3 million, or 49 cents per share, for the first quarter, with revenue of $28.2 million. Excluding charges for goodwill amortization, stock-based compensation and noncash items, it recorded a pro forma loss of $4.3 million, or 20 cents per share.