Roller derby is played on an oval track and resembles a race, in that one skater from each team, called a Jammer, must get through a pack of skaters and pass all her opponents. If the Jammer cannot get past her opponents, no points are scored by her team. There are three positions −Jammer, Blocker, and Pivot− who attempt to clear a path for their Jammer to get through. Roller derby skaters find themselves simultaneously playing offense and defense as they skate around the track.
Two teams of four Blockers each line up behind the Pivot line. The Jammers for each team are at the Jammer line, 30 feet behind the Pivot line. Once the whole pack of Blockers pass the Pivot line, the Jammers are signaled to take off. The goal is for the Jammer to lap everyone on this oval track to begin scoring points. For every opponent a jammer passes on her 2nd, 3rd, 4th, etc. pass, she scores a point. At the same time, the other four players, called Blockers, are trying to clear a path for their Jammer while impeding the progress of the opposing Jammer.
At the starting line, the Blocker with the striped helmet is the Pivot. The Pivot is often the voice of their Blockers. The Pivot might signal for her team to skate faster, so it is harder for the other team's Jammer to catch up to the pack and thus score before the clock runs out. The Pivot might signal for her team to slow down if she sees her own Jammer is trying to catch up to the pack.
The pivot is also the only Blocker that can turn into a Jammer, if the Jammer passes her helmet cover to her.
Jammers wear the star helmet. As the whistle blows to start play, the Jammers wait until the rest of the pack passes the Pivot line. When the Jammers are signaled they race off, trying to be the first to get through. The Jammer who gets cleanly through the pack first is the Lead Jammer. Only the Lead Jammer can call off the jam before the clocks ends. The advantage to being the Lead Jammer is obvious: calling off the jam prevents the other team from scoring. Of course, the Lead Jammer can strategically let the clock tick, skating around and racking up more points before the two minutes allotted for each jam elapses.
If the Jammer manages to lap everyone, including the other team's Jammer, she has scored a Grand Slam. Grand Slams are worth 5 points.
The players who are doing their best not to let the opposing Jammer pass them are the Blockers. At the starting line, the Blockers are behind the Pivot (who also serves as a Blocker). These players number three for each team, and do not have any special markings like stars or stripes on their helmets. Offensively, they create a path through the opposing blockers, so their jammer can get through. And Defensively, they block the opposing jammer, preventing her from passing them and scoring.
Blockers' defensive moves can be direct physical contact of shoulders and hips, or creating a presence that is hard to get around, such as skating left and right so the Jammer cannot get around. Blockers working together will often "build a wall," lining up so there is nowhere to go.
Offensively, the Blockers serve to help their Jammer through the pack. They can push their own Jammer forward, or be pushed by their Jammer from behind. They can help their Jammer build speed by whipping her around the track. And, true to the saying "the best offense is a good defense" a Blocker can offensively hit her opponents out of the way to make a space for her Jammer to get through.
- Grabbing or the use of hands
- Blocking with forearms
- Tripping, kicking, or blocking with feet or legs
- Hitting from behind
- Pushing, shoving, punching or holding
- Swinging elbows
- Blocking with the head
- Blocking a jammer while 10 feet ahead or 20 feet behind the pack