Abstract: A starter housing (1) for a gas discharge lamp (3) is described. The starter housing (1) comprises an outer (5) and an inner housing (10) which are arranged one inside the other in an assembled state of the starter housing (1), of which the outer housing (5) has a metal layer for electromagnetic screening. The starter housing (1) in addition comprises an inner housing tube (11) at its inner housing (10), which is surrounded in the assembled state by an outer housing tube (8) arranged at the outer housing (5), such that the inner housing tube (11) and the outer housing tube (8) together form a socket (4). Reference elements (13; 14) are provided at the tubes (8; 11) of the two housings (5; 10) such that they co-operate in the assembled state for defining the positions of the two tubes (8; 11) with respect to one another. Furthermore, a method of mounting such a starter housing (1) is disclosed.