Achmad then attended Middestand Handel School, instead of Meer Uitgebreid Lager Onderwijs, because the registration had already been closed.

[6] In those times, Achmad was an active as member of Persatuan Timur Muda, under Gerindo (Indonesian People's Movement), led by Amir Sjarifudin and Adnan Kapau Gani, and later became the chairman.

Aidit and his friends received political lectures from Sukarno, Hatta, Amir Sjarifudin, Achmad Subardjo, and Ki Hajar Dewantoro.

Lukman, Sidik Kertapati, Chalid Rasjidi, and the other young men studied politics at Asrama Kemerdekaan founded by Rear Admiral Maeda and headed by Wikana.

[10] On 5 November, Aidit, Alizar Thaib, and the other API member attacked Koninklijk Nederlands Indisch Leger's post but eventually were arrested.

In August, the three became members of the Central Committee, respectively responsible for land affair, agitation and propaganda, and relation to other organizations.

[17] After the 1948 affair, the four young members of the Politburo, Aidit, Njoto, Lukman, and Sudisman replaced the old leaders in January 1951 as a result of the fifth congress of the party.

Aidit was appointed as the secretary general of the party, which was later renamed as chairman, while Njoto and Lukman as his deputies.

[19] During the August 1951 mass arrests of communists, Aidit went into hiding with Njoto and Lukman, while thousands of the party's members and leaders were detained without charge.

Though a Marxist, Aidit submitted to Sukarno's Marhaenism[20] policy and allowed the party to grow without any overt intentions towards power.

He set up a number of programs including the Pemuda Rakyat for the youth, and Gerwani, a women's league.

[21] Minister of Education Prijono also attended the event and gave a speech which invited to pay more attention to the Indonesian film industry as an important aspect in building morals in society.

There Aidit wrote a letter of the PKI view of the coup which was read by Njoto during a cabinet meeting in Bogor.

[3] According to Zulkifli & Hidayat, on 22 November Aidit was arrested by a search party led by Colonel Yasir Hadibroto in a house in Sambeng Village, Solo.

[19] Aidit sympathized with Musso's Jalan Baru untuk Republik Indonesia (A New Road for Indonesian Republic), though he stated that the Madiun Affair was just "children's games".

In a similar fashion to Adolf Hitler in the Western world, Aidit gained a negative stigma and reputation as a symbol of evil in the Indonesian society, due to the atrocities and violence committed by the Communist Party under his leadership.