In 1911, he was awarded a doctorate in Leipzig; his thesis, written under the direction of Bücher,[1] was titled Zur industriellen Entwicklung Rumäniens: die voratufen des Fabriksystems in der Walachei ("On the industrial development of Romania: the forerunners of the factory system in Wallachia").

[2] As one of the leaders in the parliamentary opposition to the Alexandru Averescu government, he was at the center of a scandal in July 1921: during a prolonged debate, he was addressed an insult by the People's Party politician Constantin Argetoianu; promptly, the National Liberal Party (PNL) leader Ion G. Duca expressed his sympathy, and helped weaken political support for Averescu (the cabinet was to fall in autumn of that year).

Madgearu was initially supportive of King Carol II, whom his party had helped bring to power, and remained sympathetic despite the confrontation between the monarch and the PNȚ leader Maniu.

[4] According to the ironic account given by Petre Pandrea, the connection was tested by intrigue, after the writers Sergiu Dan and Ion Vinea allegedly stole a text by Madgearu (which was supposed to be published in Dreptatea), forged it by adding statements critical of Carol's policies, and sold it to Madgearu's main adversary inside the party, Mihail Manoilescu (Carol himself dismissed the letter as a fake, contributing to the ultimate PNȚ inner-conflict that caused Manoilescu to leave the group).

According to the PNȚ activist Ioan Hudiță, Madgearu, with Ion Mihalache and Mihai Popovici, continued to support the king, and, after 1938, considered joining the National Renaissance Front.

Later in that year, after the remains of Corneliu Zelea Codreanu were discovered at Jilava Prison (and the conclusion was drawn that he had been murdered on the orders of King Carol), Madgearu and Nicolae Iorga were among the victims of a wave of assassinations carried out in reprisal.

Hours after the Jilava Massacre, Madgearu was attacked in his Bucharest house, kidnapped, and taken to the Snagov forest, where he was shot[6] by five members of the Iron Guard, who discharged their pistols in bursts into his back.

[9] However, condemnation of the actions was widespread, and the resulting negative image probably contributed in rallying political forces behind traditional authorities, and the eventual ousting of the Guard by the Ion Antonescu-led Romanian Army (January 1941; see also Romania during World War II).

[11] The death squad leader, Boeru, would later be recruited by the foreign intelligence arm of the Securitate, with the mission of spying on the legionary groups that had taken refuge in the West.

[20] Building on the ideas of Alexander Chayanov, he argued that Eastern Europe in its entirety had evaded Western developments, and was home to distinct economic and social patterns.

[2] In 1919, upon the creation of the Peasants' Party, Madgearu wrote: "If the methods of various socialist parties differ, if the majority of the socialist world does not believe in the means of Russian Marxism, their common goal is the very same.If, in a state where the majority of the population is comprised of industrial proletarians, the tendency of socialism to conquer political power may be viewed as a natural and justified development, in a state where the proletariat is a minority such efforts cannot ever correspond with the natural evolution of things.Nevertheless, the Russian example shows that the possibility for a dictatorship of the proletariat, even in a country where [the proletariat] is manifestly numerically inferior, is not excluded if the largest segment of the population is amorphous and politically inert as was the case of the peasantry in the Muscovite Empire [sic].Within its new borders [that is, those of Greater Romania], Romania endures as an agrarian-industrial state, in which the rural inhabitants shall form more than three quarters of the population.

As the a labor force with medium qualification was missing in Romania, Madgearu called for the development of a proper training system which was to provide skilled professionals for the industry.

[22] In this context, he, as much as the Peasants' Party leader Ion Mihalache, supported cooperative farming (with it, he primordially aimed to preserve the small-scale rural holding, which he saw as a viable economic cell for a relative future).