1. Descriptive approach
2. Functional approach
Descriptive approach:
Explores the traits and characteristics a person is expected to have to be considered as a leader.
Functional Approach:
Explores the things is expected to do in order to be regarded as a leader.
Strengths of Functional Theories of Leadership
1. Not having to depend solely on the formal authority and power vested to a leader by his organization.
2. The leader can adopt different styles of leadership depending on the circumstances.
Leadership from Social Exchaneg theory Perspective:
Social exchange theory assumes that all human relationships are formed by the use of a subjective cost-benefit analysis and the comparison of alternatives. For example, when a person perceives the costs of a relationship as outweighing the perceived benefits, then the theory predicts that the person will choose to leave the relationship. The theory has roots ineconomics, psychology and sociology.
It assumes that there is a "reciprocal causality" between the leader and the followers.
That means the followers expect a certain outcome of the leadership.
Leader also expects some satisfaction when the followers do things that they are expected to do.
Reciprocal Causality
The concept of Reciprocal Causality says that two events influence each other simultaneously. Consider the two events, A and B. These events influence each other reciprocally if both A influences B and B influences A. A dramatic example of a situation in which two events influence each other reciprocally is the accident where two cars collide frontally.
Two models of leadeship arise from the Social Exchange Theory.
1. Action Centred Leadership (ACL) Model
2. Vertical Dyad Leadership (VDL) Model
John Adair Action Centred Leadership Model

This theory states that the leader is expented to do three interrelated functions:
1. Task related function
2. Team related function
3. Individual related function
Adair said that leaders should therefore concentrate on:
1. Task Completion (achieve the task)
2. Creating and sustaining a group of people that work together as a team (build and sustain a team) and
3. Development of individuals within the team (develop the individual).
It is clear that the individuals make up teams and teams in turn accomplish tasks, thus the three are interrelated. just one week individual can weaken the team, and such an unstable team will not accomplish the task.
Leadership functions:
1. Defining all tasks so that goals and objectives are SMART (Specific, Measurable, Achievable, Realistic and Time-Constrained).
2. Regular team briefings to make the team aware and to motivate them.
3. Motivating- successful and efficient task completion is dependant on motivated teams.
4. Organising: to prevent wastage resources and the loss of efficiency.
5. Planning: Tasks need to be planned with regards to the objectives, timescales and individual responsibilities. Planning should include contingencies.
6. A leader should constantly evaluate prior to, during and after events. This should include an evaluation of performance, training for individuals and lessons from previous experiences.
7. A leader needs to control a number of areas including maintaining overall control of the project, implementation of good control systems, and they need to possess self control.
To perform the above functions, the leader should have the following skills:
1. Having knowledge of the behavioural process of the individual members of the group and taking remedial action to resolve any problems arising from them.
2. Ability to see which of the afore mentioned functions needs attention.
3. Interpersonal skills needed to bring about the balance between the three afrementioned functions.
Vertical Dyad Leadership Model
The Leader-Member Exchange theory (shortly LMX theory) occupies a unique position among leadership theories because of its focus on the dyadic relationship between leader and follower. LMX theory was originally referred to as Vertical Dyad Linkage (VDL) theory by Dansereau, Graen & Haga in 1975.
1. There is no one leadership relationship between the leader and the followers, they vary from time to time.
2. The leader is expected to have a multiplicity of vertical relationships between different followers as they are different from one to the other.

According to VDL, there are only two types of relationships
1. In-group member relationship
2. Out-group member relationshipIn-group members;
1. Thye are expected to do more than the minimum requirement.2. They are expected to take the initiative in respect to certain activities.
3. Taken in confidence that others in the group.4. They are allowed some flexibility in performing theri functions.
Out-group members:
1. These members are expected to do he minimum.
2. Taking initiatives is not expected so much from them.3. Not much of flexibility offered to perform their duties.
4. They remain at a distance from the leader.Followers get into one of these two groups based on:
* how well they work with the leader
* how well the leader works with them
* their personalities
* role responsibilities they assume
* follower’s competencies and accomplishments
1. Leader
2. In-group members3. Out-group members
*Leder has to use his authority more than personal relattionship to get things done from the out group members.*Out-group members tend to use in-group members to get things done from the leader.
*Out-group members have to be under obligation to the in-group members for the benefits that they get from thel leader through the in-group members.In-group and out-group relationships can be found in both formal and informal groups.
Picture Credit:
http://leadershipchamps.wordpress.com/2008/04/21/leader-member-exchange-lmx-theory/