The Septembrine Conspiracy was an attempted assassination of Simón Bolívar when he was president of Gran Colombia. It occurred in Bogotá on September 25, 1828. Three dozen attackers, commanded by Commander Pedro Carujo, forcefully entered the Presidential Palace at midnight. After killing the guards, they went to Bolívar's room. Bolívar managed to escape through the window with the help of his partner Manuela Sáenz. In the trials that followed the attack, his main opponent, General Francisco de Paula Santander, was condemned to death, but Bolívar spared his life and exiled him instead. The events influenced the disintegration of Gran Colombia three years later.

The government of Gran Colombia was highly centralized, with military rulers who often disregarded the laws of the 1821 constitution. Many regions within Gran Colombia had previously had federalist systems of government and had been promised autonomy, but these promises had been ignored by the central government. As a result, there were numerous uprisings and revolts in response to the military's abuse of authority and use of fear to control the population. These rebellions were fueled by the demands of local leaders and the general population for more autonomy and respect for their rights.

Bolívar agreed to be the ruler of Peru, but by 1826 he had to leave a Council of State in charge in Lima, as he needed to negotiate with the leaders of the La Cosiata uprising. Bolívar had left instructions to complete the process of instituting a new constitution in Peru and Bolivia, which was eventually carried out. However, in January 1827, the Peruvians rebelled, claiming that the new constitution had been forced upon them through an irregular process that violated their laws. The Peruvians nullified the constitution and removed Bolívar as a potential ruler of Peru.

The proposal for a lifelong constitution was also presented to the Convention of Ocaña, but it was rejected, and by June 10, 1828, no agreement had been reached. On August 27, 1828, Bolívar signed a decree dissolving Congress, imposing a military regime, and declaring himself dictator, which further fueled social discontent towards the government of the time.

Opposition to Bolívar had grown among the Neogranadine liberals, especially after he declared himself dictator. These liberals had formed secret societies called "SSP" (Parliamentary Socratic Society, in Spanish: Sociedad Socrata Parlamental), similar to those of the French Revolution. Mostly made up of students and intellectuals, these societies met to discuss political issues. At one of these meetings, Luis Vargas Tejada made his famous speech:

Si de Bolívar la letra con que empieza
y aquélla con la que acaba le quitamos,
«oliva» de la paz símbolo hallamos.
Esto quiere decir que la cabeza
al tirano y los pies cortar debemos
si es que una paz durable apetecemos.

If from Bolívar the letter with which it begins
and the one with which it ends we take away,
«olive» of peace symbol we find.
This means that the head
to the tyrant and the feet to cut we must
if we want a lasting peace.

From one of those meetings in early September of that year came the idea of killing Bolívar. To do this, they attempted to gain supporters in the Armed Forces, recruiting veterans, reservists and sergeants, including those expelled or about to be expelled for their misconduct.