She has made many breakthroughs in engineering. Klein's research focuses on the area of sol-gel science, a low-temperature process for making ceramic coatings. Her most important contribution to science has been the development of electrochromic window coatings that can be lightened or darkened through the use of a dimmer attached to a battery. This window coating is unique because it is manually controlled and can reflect the heat away, while still transmitting light in the summer or permit the solar heat in winter. This new development is more efficient than blinds, curtains, or tinted windows and can save on heating and cooling costs in the home or office.
Klein is also noteworthy for her status at Rutgers University: she was the first female faculty member in the Rutgers School of Engineering (1977), the first female faculty member in the department of Materials Science and Engineering, the first female faculty member elevated to the distinguished PII rank, and, as of January, 2008, the only female professor in the department. As President of the Rutgers AAUP chapter Klein also concluded groundbreaking negotiations that lead to novel methods for expanding the number of tenure track faculty at Rutgers that have been cited  as potential models for faculty efforts to halt the attrition in numbers of tenure track faculty.