Hamilton will move seven sports from the Liberty League into the New England Small College Athletic Conference, fully integrating the school’s 28-sport athletics program into the NESCAC in 2011-12.

College officials said they are taking the action, which was approved Wednesday by NESCAC member institutions’ presidents, because its affiliation with both leagues “has been complicated and confusing to prospective students.”

The sports are men’s and women’s basketball, field hockey, men’s and women’s lacrosse, and men’s and women’s soccer. Hamilton’s teams in those sports have competed in the Liberty League (known before 2004-05 as the Upstate Collegiate Athletic Association) since 1995.

“We are pleased to welcome Hamilton College into the NESCAC as a full participant,” said Bowdoin President Barry Mills, chair of the NESCAC presidents. “The NESCAC places a high value on collegiality, and in making this decision, the conference recognizes its leadership position as a group guided by the highest educational standards and academic principles.”

The NESCAC, whose roots date to 1955 but was formally established as a playing conference in 1999, includes 11 highly selective liberal arts colleges and universities that describe themselves as “committed to establishing common boundaries to keep athletics strong but in proportion to the overall academic mission of the member institutions.”

It sponsors 26 championship sports – 13 for men and 13 for women.

“I am grateful to my fellow NESCAC presidents for the collegiality they showed Hamilton in reaching this decision,” said Joan Hinde Stewart, the school’s president, who also expressed gratitude to Liberty League presidents, athletics directors and coaches.

“We greatly appreciate the cooperative way in which our colleges have worked to provide opportunities for our student-athletes,” she said of the New York league, which would have nine members after Hamilton’s departure.