This research explores the determinants of the probability of having credit debt, as well as the determinants of the severity of credit card debt. Credit card debt includes revolving credit debt and petty installment loan. The severity of credit card debt was measured by the duration of revolving credit debt and the amount of petty installment loans. Analysis of behavioral data from a Chinese commercial bank showed a significant difference between the determinants of the probability of having credit card debt and the determinants of the severity of credit card debt. Specifically, credit limit, gender, length of ownership of a credit card, and the total credit card expenditure were closely related to the likelihood of having revolving credit debt and to the duration of revolving credit debt. However, age, the square of age, credit ranking, and risk ranking were significantly correlated with the likelihood of having revolving credit debt rather than the duration of revolving credit debt. Credit card balance had a special influence on the duration of revolving credit debt. Compared with revolving credit debt, petty installment loan had few significantly related factors. Both age and the square of age could significantly predict both the likelihood of having petty installment loan and amount of petty installment loan. Credit ranking, risk ranking, and gender predicted the likelihood of having petty installment loan but did not correlate with the amount of petty installment loan. The frequency of petty installment use was closely related to the amount of petty installment loan. Copyright © 2014 John Wiley & Sons, Ltd.