BackgroundDepression is a prevalent and severe disorder associated with considerable stigma. This stigma contributes to the suffering and impedes help seeking behaviour of those affected. Stigma can be influenced by causal beliefs about depression and personal contact with people suffering from depression. The aim of this study was to investigate (1) the associations between beliefs about the aetiology of depression and personal / perceived stigma, as well as (2) a possible moderating effect of personal contact with people with depression on these associations.MethodsStigma, causal beliefs, and contact with depression were assessed in a representative online survey among German adults (N = 5,000). Multiple regression analyses were performed with contact levels (unaffected vs. personally affected (diagnosed) vs. personally affected (undiagnosed) vs. affected by relatives with depression vs. persons who treat depression) and causal beliefs (biogenetic vs. psychosocial vs. lifestyle) as predictor variables for personal and perceived stigma as dependent variables.ResultsHigher personal stigma was associated with lifestyle causal beliefs (p< .001,f²= 0.07), lower personal stigma with biogenetic (p= .006,f²= 0.01) and psychosocial (p <.001,f²= 0.02) causal beliefs. A positive interaction between psychosocial beliefs and the contact group “relatives” (p = .039) further suggests that this contact group does not benefit so strongly from psychosocial causal beliefs regarding personal stigma. Higher perceived stigma was associated with psychosocial (p< .001,f²= 0.01) and lifestyle (p< .011,f²= 0.01) causal beliefs. Regarding contact levels, the “unaffected” had significantly higher personal stigma scores than each of the other contact groups (p <.001). The contact group “affected (diagnosed)” had significantly higher perceived stigma scores than “unaffected”.ConclusionsThe available data show that anti-stigma campaigns should clearly communicate, that depression is not caused by an unfavorable lifestyle. In general, psychosocial or biological explanatory models should be explained. Especially for the target group “relatives of depressive patients”, who can be an important support for patients, education about biogenetic explanatory models should be provided. However, it is important to note that causal beliefs are only one of many factors that impact on stigma.Supplementary InformationThe online version contains supplementary material available at 10.1186/s12888-023-04907-5.