Teresa Pica, 66, of Philadelphia, a professor in the University of Pennsylvania Graduate School of Education and a leading expert in the field of second language acquisition, died Tuesday, Nov. 15, at home of complications from viral encephalitis.

She had been ill since March after returning from a lecture abroad, said her sister, Anna Marie Goldberg.

Dr. Pica's influence on the theory and practice of second language acquisition was groundbreaking, according to biographical material Penn made public.

She championed the idea that students learn best when using a second language in task-based, face-to-face interactions. Although it flew in the face of thinking in the 1980s, that concept is now at the core of teaching and research, said Nancy Hornberger, a professor of education at Penn.

Although she was excited by theory, Dr. Pica never lost sight of the practical applications of her work. Much of her research focused on how best to use task-based interaction in the classroom. She shared her expertise by leading workshops for teachers around the world.

Her students remembered Dr. Pica as a tireless teacher and mentor who decorated her office with their photos. Some of the master's degree and doctoral candidates she guided have gone on to become leaders in the field themselves, her former colleagues and students at Penn said.

"They were her children, in a sense," said Jiyoon Lee, a former student who was working closely with Dr. Pica at the time of her death. "She was proud of all of us."

Her students recalled Dr. Pica's genuine interest and power of memory; when greeting former students she had not seen for years, Dr. Pica would ask about their spouses and children by name.

"I was always awed at how she was able to connect with each and every one of us on a really personal level," said Anne Pomerantz, who now teaches at Penn's graduate school of education.

Warm and welcoming, Dr. Pica nonetheless held her students to high standards and pushed them to excel. But she pushed herself, too, quickly returning students' e-mails and giving feedback on dissertation chapters within a few hours of receiving them.

She never retired, instead spending her final hours giving feedback on her students' work, her sister and Lee said.

Dr. Pica was a constant presence at academic conferences, where she amused her colleagues with her "wicked sense of humor," said Larry Selinker, a retired New York University professor and pioneer in the field of second language acquisition.

She lectured frequently at universities in the United States and abroad, was a member of the editorial boards of leading journals in her field, and won numerous academic honors.

She was also an avid fan of the New York Giants and the Phillies.

Known to her family and friends as Tere, she was born in Bridgeport, Conn., and grew up in Trumbull, where she graduated from Trumbull High School in 1963.

Dr. Pica graduated in 1967 from the College of New Rochelle with a bachelor's degree in English and speech communications. She earned a master's degree in speech pathology from Columbia University in New York City in 1969.

Soon after graduating, she worked as a speech therapist in the Easton-Redding, Conn., school system. She moved to Philadelphia in the late 1970s to study at Penn.

She earned her doctorate in educational linguistics from Penn's Graduate School of Education in 1982 and went to work as an assistant professor at the school in 1983.

At the time of her death, in addition to her professorship, Dr. Pica was director of the school's Teaching English to Speakers of Other Languages program.

She was also codirector of the Penn Lauder Center for International Business Education and Research Summer Institute.

Dr. Pica was married to Robert Hamilton, who died three years ago of multiple sclerosis.

In addition to her sister, Dr. Pica is survived by a niece and two great-nieces.

A memorial service is planned for 2 p.m. Saturday, Dec. 3, at St. Clement's Episcopal Church, 2013 Appletree St., Philadelphia 19103. Burial is private.

A memorial scholarship has been established, the Dr. Teresa Pica Memorial Scholarship Fund, University of Pennsylvania Graduate School of Education, 3700 Walnut St., Philadelphia 19104, Attention: Alexis Wolson.

Contact staff writer Bonnie L. Cook at 610-313-8232 or bcook@phillynews.com.