Action learning can be defined as a process in which a group of people come together more or less regularly to help each other to learn from their experience.
As Reg Revans used and described it, it was mostly used _across_ different organisations. That is, the participants typically came from different situations, where each of them was involved in different activities and faced individual problems. Most commonly the participants have been managers, though this is not essential.
The current practice more often now is to set up an action learning program within one organisation. It is not unusual for a team to consist of people with a common task or problem.
There may or may not be a facilitator for the learning groups which are formed. Revans mostly avoided them. Current practice, I think, is mostly to use them

In summary, action learning brings together small groups of participants with the following intentions:
• To work on and through organisational/individual issues. This is most effective when the commitment is voluntary.
• To work on real problems. Situations in which "I am part of the problem and the problem is part of me."
• To work together to check individual perceptions, clarify (and render more manageable) the issue and explore alternatives for action.
• To take action in the light of new insight. Begin to change the situation.
• Bring an account of the consequences back to the group for further shared reflection.
• To focus on learning, not only about the issue being tackled but also on what is being learned about oneself. This is essential to turn developing understanding into learning that can be transferred to other situations.
• To be aware of group processes and develop effective ways of working together.
• To provide the balance of support and challenge that enables each person to manage themselves and others more effectively.
Each group is provided with a facilitator (set adviser) whose role is to help individuals and the group to identify and develop the necessary skills.