Many people find that solving story problems is challenging. A key source of the difficulty is symbolizing problem situations. In two experiments, we tested whether diagrams promoted successful symbolization of two-operator story problems, and we tested whether diagrams that depicted the integration of operations were more beneficial than diagrams that depicted the two operations separately. Findings in the two experiments were similar but not identical. Overall, participants were more likely to generate conceptually correct equations--though not always in integrated form--in the presence of diagrams, and this pattern was driven by the beneficial effects of diagrams for participants with lower visuo-spatial abilities. Further, participants with more negative attitudes towards mathematics were more likely to generate integrated equations with diagrams that depicted the integration of operations. Thus, the effects of diagrams varied across subgroups of participants. [This paper was published in "Applied Cognitive Psychology" v35 n6 2021.]