Dissatisfied with the official investigation into the case, families of the missing students and others will later Wednesday gather in Mexico City and all across the country.
Protests were also planned as far away as London and the Bolivian capital of La Paz.
In Mexico City, demonstrators will march from the iconic Angel of Independence to the city's main Zocolo Square.
Organisers have also called for protesters to block streets and highway toll collection booths Thursday.
The 43 students of the Normal Rural School of Ayotzinapa in the southern town of Iguala went missing Sep 26 after police opened fire at them, killing six people, including three of the students, and injuring 25 others.
Following the incident, the students were seen being led away by police who authorities say were in league with a local crime gang.
Officials have excavated several mass graves near Iguala but they said the remains did not belong to those missing.
Dozens of people, including a number of policemen, have been arrested for their suspected involvement in the disappearance.
Meanwhile, in a statement Tuesday, a group of prominent Mexicans demanded that the authorities set up a Truth and Justice Commission to investigate the disappearances.