Due to the war, Vabalas-Gudaitis was forced to stay in Russia and not return to Lithuania, and consequently, he began working as a hydrologist in the Saratov Governorate.

Becoming a professor and the head of the pedagogy department in Vytautas Magnus University, Vabalas-Gudaitis held various seminars and constructed tests intended for students, which teachers of state schools received.

Privately tutoring children of wealthy parents, in 1902 Vabalas-Gudaitis graduated from the Šiauliai Gymnasium and entered Saint Petersburg State University to study physiology.

[2] After completing university in St. Petersburg and studies with Ushinsky in 1913,[1] Vabalas-Gudaitis wished to return to Lithuania to work as a teacher.

[1] The beginning of World War I a year before would not let Vabalas-Gudaitis return to Lithuania, and as a result he was forced to stay in the Russian Empire.

As Vilnius was under Russian occupation at that time due to the Lithuanian Wars of Independence, Vabalas-Gudaitis was sent over to Moscow and St. Petersburg to get acquainted with similar institutions.

[2] After the Vilna offensive, during which Vilnius fell into Polish hands, Vabalas-Gudaitis moved to Kaunas, where he began organizing courses.

In Kaunas, Vabalas-Gudaitis created a laboratory of experimental psychology, which he especially expanded in 1922 after beginning work as head of the department in the Vytautas Magnus University, later becoming a docent, and in 1927 – a professor.

According to a report by the university, Gudaitis's laboratory "researches students' intellect and detects their norms, gives advice to mothers and teachers, holds connections with similar institutions abroad".

He spent the rest of his life modifying the classification of psychological reactions based on the synergy of the nervous system, underlining that a person's behavior is the conglomeration of the traits they were born with as well as outside influences.

[2][6] Gudaitis also developed machines for reaction testing,[7] and held teachers in high regard as the carriers of responsibility for the future of the country.

While researching criminology, Vabalas-Gudaitis also wrote on the origins of different criminal types, postulating that nativists hold inheritance as the highest value and as such do not solve the problem but put it to the "dark past", while empiricists look for the causes of the crime in environmental, external factors; Vabalas-Gudaitis claimed that in reality, there is a synergy between internal and external psychophysical human forces, and therefore crime arises from a person's biosocial interaction.

In 1932, Vabalas-Gudaitis let Lithuanian psychologist Vladimiras Lazersonas [lt] hold lectures on experimental psychology instead of him, retiring to a more writing-based lifestyle.

After the Soviet re-occupation of Lithuania, Vabalas-Gudaitis was once again made head of the pedagogy department at Vilnius University, and received the title of professor.