The capacity to remember a sequence of items is critical to various cognitive functions, including short-term memory (STM). The information in a sequence is at least twofold, including item-identity and the serial order of items. In both the verbal and nonverbal domains, it is well established that the STM capacity supporting serial order information dissociates from item-identity information. The research in this thesis addresses whether the serial order STM capacity is shared for sequences in different content domains. One hypothesis is that there are domain-specific serial order STM capacities exclusive to distinct domains, whereas an alternative hypothesis is that one general serial order STM capacity is being recruited for sequences in different domains. Although various studies have explored the domain-generality of serial order STM capacity, a conclusive result has not been reached. In the thesis, I examine these two hypotheses from an individual difference perspective. The two hypotheses were operationalized by manifest variables from four sequence matching tasks with verbal stimuli (letters and words) and nonverbal stimuli (locations and arrows). Participants had to decide whether two six-item sequences were identical. Non-identical trials differed either by a single item identity or by a transposition of two adjacent items, and they presumably were supported by item and serial order STM capacity, respectively. Accuracy was used to manifest individual differences at detecting item and order changes in STM at the behavioral level. With nested model comparison, the domain-specific model represented by distinct item and serial order STM capacities in both domains best fits the data from 153 participants. On this basis, the current study supports the hypothesis that serial order STM capacity is domain-specific.