Upon completing her bachelor's degree, Dr. Marcinek worked as a critical-care nurse in the coronary unit of what is now UPMC-Presbyterian. Other previous employment included 10 years on the faculty of the West Virginia University School of Nursing, where she progressed through the ranks to become an associate professor. During her tenure there, she received the West Virginia University School of Nursing Outstanding Teacher Award for two consecutive years.

She has worked at Cal U since 1983, when she initiated the RN to BSN program. From 1985-2004, Marcinek chaired the nursing program, steering it through three national accreditation visits from the National League for Nursing and the Commission on Collegiate Nursing Education.

At Cal U, she has served on numerous University committees, including the Science and Technology Council, Department Chairs Forum, Provost Council, University Curriculum Committee and the State System of Higher Education Student Learning Assessment Resource Group.

In 2001, she received the Cal U Presidential Faculty Award for Teaching. She accepted the position of interim associate provost in 2004 and served until 2006, when she decided to return to the faculty.