Purpose: In 2017, the European Alliance against Depression (EAAD) programme was introduced in the Netherlands through the creation of six local Suicide Prevention Action Networks (SUPRANET Community). This programme consists of interventions on four levels: (1) a public awareness campaign, (2) training local gatekeepers, (3) targeting high-risk persons in the community and (4) training of primary care professionals. This study aims to gain insight into the effectiveness of the SUPRANET programme on attitudinal changes in the general public by studying the exposure–response relationship. Methods: A repeated cross-sectional design, using general population surveys to measure key variables over time. The surveys were conducted in the six intervention regions (N = 2586) and in the Netherlands as a whole as a control region (N = 4187) and include questions on socio-demographic variables, brand awareness of the Dutch helpline, perceived taboo on suicide, attitudes towards depression and help-seeking. To examine the exposure–response relationship, regions were differentiated into 3 groups: low, medium and high exposure of the SUPRANET programme. Results: The results revealed that respondents in the intervention regions considered professional help to be more valuable and were more likely to be familiar with the Dutch helpline than respondents in the control region. In the exposure–response analyses, the grading of effects was too small to reach statistical significance. Conclusion: Our study provides the first evidence for the effectiveness of the SUPRANET Community programme on creating attitudinal change in the general public.