Cooperative base groups are long-term cooperative learning groups with stable membership whose primary responsibilities are to help students provide each other with support, encouragement, and assistance in completing assignments and hold each other accountable for striving to learn. Typically, cooperative base groups (1) are heterogeneous in membership (especially in terms of achievement, motivation, and task orientation), (2) meet regularly (daily or biweekly), and (3) last for at least the duration of a class (a semester or year) and preferably until the students are graduated. When students know that the cooperative base group will stay together until each member is graduated, they become committed to finding ways to motivate and encourage their groupmates. Problems in working with each other cannot be ignored or waited out.

The activities for base groups can include:

• Academic support tasks such as checking to see what assignments each member has and what assistance is needed. Members can give each other advice on how to study and “survive” in school. They can prepare each other to take tests and go over the questions missed after the test. And they can share their areas of expertise (such as art or computers) with each other. Above all, members monitor each other's academic progress and make sure all members are achieving.
• Routine tasks such as taking attendance or collecting homework.
• Personal support tasks such as listening sympathetically when a member has problems with parents or friends, having general discussions about life, giving each other advice about relationships, and helping each other solve nonacademic problems. Teachers may increase the likelihood of personal support through trust-building exercises, such as having members share their favorite movie, a childhood experience, a memory, and so forth.