The Jammer is the one skater on the team with the ability to score points. She starts each jam behind the rear line (the Jammer line) and wears the helmet cover with the star on it. She needs to wait until the second, double whistle is blown before she can cross the Jammer line to start the jam. Strategically, it is her responsibility to get Lead Jammer status, score points, and then call off the jam. As the sole points-scorer for her team, if she commits a penalty and is sent to the box, she not only loses Lead Jammer status if she has it, but she also gives the opposing team the duration of her penalty time (usually 60 seconds) the opportunity to score points unopposed.
The Pivot is a special Blocker who wears a striped helmet cover on her head. She is the only skater allowed to line up at the start of the jam with her skate touching the starting line (the Pivot line), and wears the helmet cover with the stripe on it. When the Pivot is lined up with her skate touching the Pivot line, all other Blockers must line up with their hips behind her hips. In practice, Pivots are often responsible for calling out strategy to the rest of the Blockers. The Pivot also has the ability to receive a star pass from the Jammer—a rare maneuver that transforms the Pivot into her team's Jammer when the star helmet cover is passed from Jammer to Pivot and placed on the pivot's head.
Teams field four Blockers per jam (one of whom is usually a Pivot, although fielding a Pivot Blocker is not mandatory). Blockers do everything they can to legally prevent the opposing Jammer from passing them, while at the same time assisting their own Jammer through the pack past opposing Blockers. As a result, roller derby is a unique sport in which players play offense and defense simultaneously.