In May 1919, Grzegorzewska and Joteyko returned to Poland, soon after the establishment of the
Second Polish Republic. After a few months began working as an assistant in the
Ministry of Religious Affairs and Public Education. She was tasked with managing the development of
special education for schools, institutions and educators. At the time, the only special education facilities in the country consisted of bureaus for the blind in
Bydgoszcz and
Lviv, a bureau for the deaf in Warsaw, and supplementary schools to assist with support services in Warsaw and
Łódź. As Joteyko had been denied placement at the
University of Warsaw, Grzegorzewska helped her find work as a lecturer at the National Pedagogical Institute () and ()in Warsaw. Though at the time in Poland, there were limited facilities which had been established for deaf, blind, and intellectually disabled people, there was no national system to address the education of those living with physical or mental impairments. Grzegorzewska aimed to implement educational methods she designed, mandatory training for teachers, and on-going research projects to assess the system over time. Her educational method adopted a holistic approach which included addressing care, barriers to everyday functioning, and the education of disabled people, but also their social integration and socio-professional development. It approached evaluating chronically ill, disabled, or socially maladjusted children from an interdisciplinary, scientific stance, rather than focusing on their perceived defects. After a three-year period, in which she reorganized her teaching course several times, Grzegorzewska founded the () in 1922. She served as the director of the Institute from its inception until her death. In 1924, she founded the journal,
Special School () to publish about the field and spur scientific work to develop "innovative methods of revalidation" for maladjusted and disabled children, which she directed to the end of her life. When Joteyko's heart condition became worse in 1927, Grzegorzewska took charge of her care until her death the following year. In 1930 founded and directed the State Teacher's Institute (), to give educators a facility for improving their skills through further education and training on teaching techniques. She was dismissed from the Teacher's Institute in 1935 because she opposed the
authoritarian rule advocated by the
Sanacja movement. In 1927 she published a book,
Psychological Structure of Visual and Tactile Reading (). She participated in many conferences, including the 4th Congress of the International New Education League held in 1927 in
Locarno, Switzerland; the 2nd Congress of Teachers of Special Schools hosted in 1934; and the 1st National Children's Congress of 1938. With the onset of
World War II in 1939, the Special Education Institute was closed, and Grzegorzewska began working as a nurse in an army hospital run by the
Polish Red Cross. Between 1939 and 1944, she taught at Special School No. 177 in Warsaw and participated in the
clandestine educational system. Active in the
Polish resistance movement, she distributed arms and pamphlets; joined
Żegota, providing "meritorious" assistance to
Jews; and took part in hiding Jews to save their lives. She served as a member of
Ochota's health patrol during the
Warsaw Uprising. During the uprising, her house was destroyed, and in it, unpublished manuscripts of two of her books, second volume of
Psychology of the Deaf (), first volume published in 1930) and ''Teacher's Personality'' (). After
Poland was liberated in 1945, Grzegorzewska reactivated the Special Education Institute, which had been destroyed during the conflict. Recognizing that 30% of the teachers had died in the war, she initiated programs to help train new teachers quickly. The Polish Teachers' Union was reestablished and she began research to evaluate existing educational programs, teachers' socio-economic status, and the role of schools in their communities, among other topics. In 1947, Grzegorzewska published the first volume of her
magnum opus Letters to a Young Teacher () in which she set forth her thoughts on the relationship of teachers to their students and the impact that educators have on a pupil's development. In the book, she discussed solutions to improve the lives of people with disabilities by overcoming their functional limitations, including their living conditions. She stressed that lessons should be grounded in flexible activity, which met the abilities of students and stimulated their learning. She noted the importance of adequate breaks to prevent overstimulation. Creating a detailed classification system, she advocated that the spectrum of disabilities was extremely broad and required teachers to individualize training to meet students' needs. She chose the title to convey that the information in the book was a dialogue, intended to generate reflection and inspiration, as well as feedback from teachers. The entire work contained 24 letters, published in 3 volumes, between 1947 and 1961. The first volume along with practical advice, focused on building community among teachers, encouraging them to help each other. Other letters gave historic information on innovators in education, and still others discussed humanitarian and ethical values as the keys to self-knowledge and coping mechanisms for change, which could in turn motivate and inspire others. She was less interested in structure of materials and more focused upon providing assistance which recognized the dignity and right to equality of all life. The volumes were influential in the international development of thought on education in general, as well as special education. In 1950, Grzegorzewska introduced
extramural and postgraduate courses at the Institute of Special Education, but in March, the school was renamed the State College of Special Education () and a state curricula was introduced. During the remainder of the
Stalinist period, her activities were "received coldly" by those in power in the
Polish People's Republic, as the official position was that people with disabilities needed no special consideration. Teachers who were judged to be insufficiently
Marxist were dismissed or demoted and teacher training was eliminated. She fought to protect special education and people with disabilities to prevent them from being harmed by
production quotas and policies based on fear and suspicion. putting her job in jeopardy. When the
1956 thaw granted the Polish government greater autonomy from Russian policies, she regained the support of authorities and the name of the Institute was reestablished. From 1957 to 1960 she was a full professor at the
University of Warsaw and the chair of the first Polish Department of Special Pedagogy. She introduced tertiary courses in special education for the University of Warsaw. Her later major works include
Analysis of Compensation Occurrences among the Deaf and Mute (, 1959) and
Selection of Works (, 1964). Her work in science and the Polish education system were honored with numerous awards and distinctions at the end of her life. ==Death and legacy==