PurposeDesign of architecture, engineering and construction (AEC) project organizations expose project management practitioners (PMPs) to poor mental health due to the influence of project organization designs on project management activities assigned to the PMPs. The AEC project organization design comprises the integration of permanent organization, project organization and external environment layers. In spite of the link between project organization design and mental health, limited studies have examined the impact of permanent organization factors, project organization factors and external environmental factors on mental health management practices. Therefore, this study aims to examine the interactive relationships between permanent organization factors, project organization factors, external environment factors and mental health management indicators.Design/methodology/approachFour organizational theories: institutional theory, agency theory and resource-based theory were integrated to develop a theoretical model guiding the aim of the study. Eighty-two survey data were collected from PMPs in AEC firms in Australia. Structural equation modelling was used to test the relationships between the constructs.FindingsThe study found that mental health management indicators are predicted by the interactive and direct effects of permanent organizational factors, project organizational factors and external environmental factors. The results of the interactive effects of the factors and mental health management indicators revealed that 20 of 26 proposed hypotheses were supported. Based on the established hypotheses, economic factors, technological factors, environmental factors, legal factors and organizational culture positively correlated with mental health management indicators. Likewise, human resources management (HRM), corporate governance, project governance and integrated project delivery (IPD) positively impact mental health management indicators. However, political factors, social factors, knowledge management and project management skills negatively impact mental health management indicators. Moreover, political factors, economic factors, technological factors, environmental factors, legal factors and organizational culture are positively related to corporate governance. Additionally, organizational culture positively impacts corporate governance, project governance and HRM, whereas project governance positively correlated with IPD and knowledge management.Originality/valueThe findings provide guidelines to AEC firms on achieving positive mental health management indicators through concentration on project organization design.