Social norms as catalysts for sustainable procurement: the mediating role of willingness to pay in value-driven sourcing

Purpose This study investigates how social norms (descriptive, injunctive, and personal) act as catalysts for sustainable procurement, specifically examining the critical mediating role of Willingness to Pay (WTP) in facilitating Value-Driven Sourcing (VDS). It aims to move beyond compliance-driven approaches by understanding the behavioral and economic mechanisms that embed sustainability into organizational culture, with a focus on Small and Medium Enterprises (SMEs). Design/methodology/approach A quantitative research design was employed, utilizing a structured questionnaire administered via Google Forms to a stratified sample of 197 SME respondents. Data analysis was conducted using Structural Equation Modeling (SEM) with SmartPLS, grounded in the Norm Activation Model (NAM), to test a series of hypotheses concerning the direct and indirect relationships between Social Norms, WTP, VDS, and Actual Sustainable Procurement Behavior (ASPB). Findings The results provide strong empirical support for an extended Norm Activation Model. All three types of social norms (descriptive, injunctive, personal) have significant direct positive effects on ASPB. Crucially, WTP was validated as a pivotal mediating mechanism: both injunctive norms (H6: β = 0.14, p = 0.01) and personal norms (H7: β = 0.13, p = 0.01) significantly influence ASPB through their positive effect on WTP. Personal norms also directly drive VDS (H8) and do so indirectly via WTP (H9: β = 0.56). The model demonstrated an excellent fit, confirming the robustness of the proposed theoretical pathways. Research limitations/implications This study makes a primary theoretical contribution by empirically operationalizing the abstract 34; cost34; component of the classic Norm Activation Model. It redefines 34; incurring a cost34; from a latent psychological assumption into a measurable financial construct—Willingness to Pay. This transformation advances NAM from a theory of altruistic intention into a precise framework for predicting economic decision-making in organizational settings, effectively bridging micro-level behavioral theory with the macro-level strategic paradigm of Value-Driven Sourcing (VDS). Practical implications The findings offer actionable, evidence-based strategies. To increase WTP, organizations should move beyond generic policies and implement concrete measures such as: (1) creating explicit 34; Sustainability Premium34; budget lines to pre-approve cost premiums for certified suppliers; (2) using internal communications to highlight descriptive norms (e.g., 34; X% of peer firms now use green suppliers34;); and (3) leveraging injunctive norms by publicly showcasing client endorsements for sustainable practices. This provides a tangible 34; guarantee34; that cultivating a normative environment, when supported by formal budget allocation, directly increases WTP. Social implications By demonstrating how social norms drive sustainable procurement, the study highlights a pathway for SMEs to become agents of positive social change. WTP for sustainable products fosters demand for ethical supply chains, which can directly improve labor standards, support local communities, and promote public health through safer, greener products. This positions SME procurement not just as an economic function, but as a vital mechanism for achieving broader societal goals like equitable development and environmental justice in emerging economies. Originality/value This research is original in its explicit focus on WTP as the mediating linchpin between social norms and sustainable procurement outcomes in an SME context. It moves beyond examining norms or WTP in isolation, offering a holistic, empirically validated model that explains how normative pressures are converted into economic commitments and, ultimately, into value-driven sourcing practices.