In the fraught world of playground politics, think nice guys finish last? Guess again. A 4-week study found kind kids are happier and better liked by peers. Working with 400 9- to 11-year-olds, the universities conducting the study assigned half the group three simple positive acts per week. At the end of the study period, not only did the kids who performed those acts score higher on happiness measures (which, researchers say, aligns with research on the effect of positive behavior on adult states-of-mind), but they were also chosen by more peers for collaborative classroom activities. Sounds like following the golden rule may be a golden ticket to happier school years.