With a surprise deal to acquire the for-profit Kaplan University, announced on Thursday, Purdue University has leapfrogged into the thick of the competitive online-education market. Purdue plans to oversee the institution as a new piece of its public-university system — a free-standing arm that will cater to working adults and other nontraditional students. The purchase, conceived and executed in just five and a half months, puts Purdue in position to become a major force in an online landscape increasingly dominated by nonprofit institutions. Until now, said Purdue’s president, Mitch Daniels, the university "has basically been a spectator to this growth" in distance education, with just a few online graduate programs. Mr. Daniels, a former Republican governor of Indiana, described the acquisition as adding a "third dimension" to Purdue, along with its research-rich flagship in West Lafayette, Ind., and its regional campuses. For Kaplan and its parent company, Graham Holdings, the deal offers a potentially profitable exit strategy for an operation that has seen its bottom line battered for several years by falling enrollments. (Kaplan now has 32,000 students.) The contrast between the typical Purdue student and the military veterans, lower-income students, and members of minority groups who make up much of the enrollment at the open-access Kaplan is "stark," said Mr. Daniels. But he said the university has a responsibility to serve such students. Millions of Americans have some or no college credits, and Purdue can’t fulfill its land-grant mission "while ignoring a need so plainly in sight," he noted while unveiling the deal at a Board of Trustees meeting on Thursday. The potential financial upsides were also clearly a factor. In an interview with The Chronicle, Mr. Daniels said it was "too soon" to talk about revenue projections. "We have hope and reason for hope" that Purdue’s new acquisition will do well, he said, alluding to the fast pace of online growth at other nonprofit institutions, like Western Gover