From attitudes to actions – decoding the drivers of sustainable apparel consumption using PLS-SEM and NCA

Purpose The intention–behaviour gap is a persistent challenge in green consumption. Unless stated preferences translate into actual purchases, sustainable brand positioning and service becomes ineffective. This study aims to extend the theory of planned behaviour (TPB) to explain sustainable apparel purchase behaviour among young Indian consumers and to separate the factors that are sufficient to drive it from those that are necessary preconditions. Design/methodology/approach Using a quantitative, cross-sectional design, the study analyses 365 valid responses from an online pan-India survey. The extended TPB model is tested by combining partial least squares structural equation modelling (PLS-SEM) and necessary condition analysis (NCA) in SmartPLS 4.0 and R. Findings Purchase intention predicts purchase behaviour and attitude predicts intention. Circular economy–sustainable development goals (CESDG) awareness and green brand loyalty (GBL) significantly influence purchase behaviour, while altruistic behaviour and personal norms shape attitudes. NCA establishes eco-anxiety as a necessary but not a sufficient condition for purchase behaviour, illustrating the two methods’ complementary value. Research limitations/implications Integrating sufficiency and necessity logics yields a fuller account of how intentions become purchases. Fashion retailers and service providers should prioritise environmentally conscious young consumers, use credible sustainability labelling and build GBL through service touchpoints. The cross-sectional, single-country design limits causal and cross-cultural generalisation. Originality/value The study jointly applies PLS-SEM and NCA rarely combined in this domain and incorporates underexplored constructs such as CESDG awareness, materialism and eco-anxiety into the analysis of young consumers’ sustainable apparel behaviour, offering fresh insight into their interrelationships.