Faced with market saturation and intense competition, the credit-card industry has turned to the youth market as the final untapped market segment to sustain profitability. However, the vulnerable status of this market segment means that they might be exposed to debt accumulation and a worrisome future. Correspondingly, marketers are expected to prioritize social responsibilities without posing harm to other stakeholders. In an effort to enrich the knowledge about youth market vulnerability to credit card, this paper reports the development of several important new constructs and a structural equation model with empirical results. Following the theory of planned behavior (Ajzen, 1991), three sequential processes of consumer attitudes and patterns of credit card usage are conceptualized. Our theory argues that attitudes towards deferred gratification and instant gratification function as antecedents to consumer susceptibility to credit card effects, which subsequently affect the degrees of problematic credit debt accumulation. A sequential study of qualitative and quantitative methods was employed and the current paper reports the main results on the validity of measurement and the structural model.