During the war he worked as a military psychologist doing studies of racial hygiene in occupied Poland.

He held lectures, among other subjects, on racial hygiene, and advocated the establishment of a department for this subject.

He argued that the "biological perspective" was the most important aspect of understanding eugenics and racial hygiene.

Lundborg was extremely negative towards the Jewish people, and strongly involved with the ideology of racial hygiene.

He was a strong and influential proponent of eugenics and racial hygiene.

He thought that Germany could become strong again only if the state applied the principles of racial hygiene and eugenics to German society.

In 1924, the organization was named back to German Society for Racial Hygiene.