This paper demonstrates the importance of including non-linearities in the design of textile reinforced concrete (TRC) shells. By two cases, the influence on the buckling load of considering geometrical non-linearity and material non-linearity, but also of considering geometrical imperfections is examined. For stiff shells mainly in compression, the buckling load is significantly reduced by including imperfections, analogue to observations with steel reinforced concrete shells. For shells with a low stiffness, experiencing large deformations, a non-linear analysis is essential and the buckling load is mainly reduced by considering material non-linearity. Conclusively, the shape and boundary conditions of thin TRC shells indicate which parameters should be taken into account in their design.