Scholastic sport is a double-edged sword that can have positive or negative effects. Whether those effects are positive or negative depends on those who wield that sword--chiefly, the school's sports coach. While it is clear that coaches make a difference in ensuring that educational athletics lead to beneficial outcomes for student-athletes, a key question is what does good coaching involve? Luckily, researchers have been studying coaching effectiveness for some time and have discovered a number of important principles. Effective coaches have well thought-out coaching philosophies that align with educational athletic and school goals; share decision making with their athletes and provide rationale for their coaching actions; build strong coach-athlete relationships; create caring and supportive emotional climates; and are knowledgeable and good teachers.