“My-side bias” refers to the tendency to generate more reasons in favor of one’s own position than the other side’s position.  The present study examined effects of goal instructions with strategies and role assignment on reducing my-side bias when writing arguments.  In the pilot study, the fourth-grade students who assumed that their readers had an opposing position generated more counterarguments than the control students did.  However, they did not generate rebuttals.  In the main study, fifth grade elementary school students (N=90) wrote arguments in 3 different conditions: (a) control condition: students were given the goal of generating more counterarguments and rebuttals; (b) strategy condition: student were given those goals and a strategy for accomplishing the goals; and (c) role assignment condition: students were given the same goals and strategy, plus instructions to write like a journalist.  Students in the strategy and role assignment conditions generated more rebuttals than the students in the control condition did.  These results suggest that the strategy instruction reduced my-side bias when the students were writing arguments.  In addition, the students in the role assignment condition referred to more evidence to prove that the position that they supported was superior to the opposing position than the students in the strategy condition did.