Relational leadership and exchange theory In the last 25 years, different theories of leadership have studied the relationship between leader and follower. One of these theories is the leader-member exchange theory (or LMX), initially described by Dansereau et al. (1975). In 1978, McGregor Burns analyzed relationships between leaders and followers and defined the theory of transformational leadership, later to be modified by Bass (1985). More recently, Rost (1991, p. 102) proposed the following definition of leadership: ``leadership is an influence relationship among leaders and followers who intend real changes that reflect their mutual purposes''. These paradigms focus on the exchange relationship between leader and subordinates (relational leadership) rather than stressing the leader's qualities or behaviors (personal leadership), or the match between the leader's style with the followers and task (situational leadership). Exchange relationships have traditionally been classified in two types: economic and social (Homans, 1961; Blau, 1964). Economic exchange is based on an explicit agreement between two parties. For example, the economic exchange relationship between boss and subordinate is regulated by an employment contract specifying the rights and duties of each in relation to the other. The failure of one of the parties to carry out his or her duties can lead to a legal suit by the
other party. Social exchange, on the other hand, is based on an implicit agreement that covers non-specific obligations between the two parties. For example, a social exchange relationship between boss and subordinate could consist in the boss concerning herself with the subordinate's family needs, and the subordinate taking greater pains with his work in order to please his boss. Such obligations cannot be legally enforced, although an implicit reciprocal undertaking
does exist, based on a certain identification between the two parties.