This is a series of posts that records the cases of cohabitation in countries with semi-presidential constitutions. Cohabitation is defined as the situation where the president and prime minister are from different parties and where the president’s party is not represented in the cabinet. Presidents classed as non-party cannot generate any periods of cohabitation.

Here is my list of cohabitations under Weimar:

Jun 1920 – May 1921
President – Friedrich Ebert (SPD); PM – Konstantin Fehrenbach (Z); Government – Z, DPP, DVP

Nov 1923 – May 1925
President – Friedrich Ebert (SPD); PM – Wilhelm Marx (Z); Government – Z, DDP, DVP, BVP (until June 1924)

I do not count the following as cohabitation because of the non-party PM, but note also:
22 Nov 1922 – 13 Aug 1923
President – Friedrich Ebert (SPD); PM – Wilhelm Cuno (non-party); Government – technocrats plus Z, DPP, DVP

Sources: wikipedia lists coalition partners under PM’s name.