'''Leadership''' has been described as "a process of [[social influence]] in which 47 person can enlist the aid and [[Peer support|support]] of others in the accomplishment of a common [[task (project management)|task]]",<ref>Chemers M. (1997) ''An integrative theory of leadership''. Lawrence Erlbaum Associates, Publishers. ISBN 978-0-8058-2679-1</ref> although there are alternative definitions of leadership. For example, some understand a '''leader''' simply as somebody whom people follow, or as somebody who guides or directs others,{{citation needed|date=September 2013}} while others define leadership as "organizing a group of people to achieve a common goal".{{citation needed|date=September 2013}}

[[Leadership studies|Studies of leadership]] have produced theories involving traits,<ref name=refLocke1991>[[#refLocke1991|Locke et al. 1991]]</ref> situational interaction, function, behavior, [[Power (social and political)|power]], [[goal|vision]] and [[Value (personal and cultural)|value]]s,<ref>(Richards & Engle, 1986, p.206)</ref> [[charisma]], and intelligence, among others.

==Theories==

===Early western history===

The search for the characteristics or traits of leaders has been ongoing for centuries. Philosophical writings from Plato's ''[[The Republic (Plato)|Republic]]'' to Plutarch's ''[[Parallel Lives|Lives]]'' have explored the question "What qualities distinguish an individual as a leader?" Underlying this search was the early recognition of the importance of leadership and the assumption that leadership is rooted in the characteristics that certain individuals possess. This idea that leadership is based on individual attributes is known as the "[[trait leadership|trait theory of leadership]]".

The trait theory was explored at length in a number of works in the 19th century. Most notable are the writings of [[Thomas Carlyle]] and [[Francis Galton]], whose works have prompted decades of research.<ref>http://qualities-of-a-leader.com/trait-approach/</ref> In ''Heroes and Hero Worship'' (1841), Carlyle identified the talents, skills, and physical characteristics of men who rose to power. In Galton's ''Hereditary Genius'' (1869), he examined leadership qualities in the families of powerful men. After showing that the numbers of eminent relatives dropped off when moving from first degree to second degree relatives, Galton concluded that leadership was inherited. In other words, leaders were born, not developed. Both of these notable works lent great initial support for the notion that leadership is rooted in characteristics of the leader.

===Rise of alternative theories===

In the late 1940s and early 1950s, however, a series of qualitative reviews of these studies (e.g., Bird, 1940;<ref>Bird, C. (1940). Social Psychology. New York: Appleton-Century.</ref> Stogdill, 1948;<ref>Stogdill, R.M. (1948). Personal factors associated with leadership: A survey of the literature. Journal of Psychology, 25, 35-71.</ref> Mann, 1959<ref>Mann, R.D. (1959). A review of the relationship between personality and performance in small groups. Psychological Bulletin, 56, 241-270.</ref>) prompted researchers to take a drastically different view of the driving forces behind leadership. In reviewing the extant literature, Stogdill and Mann found that while some traits were common across a number of studies, the overall evidence suggested that persons who are leaders in one situation may not necessarily be leaders in other situations. Subsequently, leadership was no longer characterized as an enduring individual trait, as situational approaches (see alternative leadership theories below) posited that individuals can be effective in certain situations, but not others. This approach dominated much of the leadership theory and research for the next few decades.

===Reemergence of trait theory===

New methods and measurements were developed after these influential reviews that would ultimately reestablish the trait theory as a viable approach to the study of leadership. For example, improvements in researchers' use of the round robin research design methodology allowed researchers to see that individuals can and do emerge as leaders across a variety of situations and tasks.<ref name="Kenny, D.A. 1983">Kenny, D.A. & Zaccaro, S.J. (1983). An estimate of variance due to traits in leadership. Journal of Applied Psychology, 68, 678-685.</ref> Additionally, during the 1980s statistical advances allowed researchers to conduct [[meta-analysis|meta-analyses]], in which they could quantitatively analyze and summarize the findings from a wide array of studies. This advent allowed trait theorists to create a comprehensive picture of previous leadership research rather than rely on the qualitative reviews of the past. Equipped with new methods, leadership researchers revealed the following:

*Individuals can and do emerge as leaders across a variety of situations and tasks.<ref name="Kenny, D.A. 1983"/>

*Significant relationships exist between leadership emergence and such individual [[trait theory|traits]] as:

{{columns-list|3|

:*[[intelligence]]<ref name="Lord, R.G. 1986">Lord, R.G., De Vader, C.L., & Alliger, G.M. (1986). A meta-analysis of the relation between personality traits and leader perceptions: An application of validity generalization procedures. Journal of Applied Psychology, 71, 402-410.</ref>

:*adjustment<ref name="Lord, R.G. 1986"/>

:*[[extraversion]]<ref name="Lord, R.G. 1986"/>

:*[[conscientiousness]]<ref>Arvey, R.D., Rotundo, M., Johnson, W., Zhang, Z., & McGue, M. (2006). The determinants of leadership role occupancy: Genetic and personality factors. The Leadership Quarterly, 17, 1-20.</ref><ref name="Judge, T.A. 2002">Judge, T.A., Bono, J.E., Ilies, R., & Gerhardt, M.W. (2002). Personality and leadership: A qualitative and quantitative review. Journal of Applied Psychology, 87, 765-780.</ref><ref>Tagger, S., Hackett, R., Saha, S. (1999). Leadership emergence in autonomous work teams: Antecedents and outcomes. ''[[Personnel Psychology]]'', 52, 899-926. http://onlinelibrary.wiley.com/doi/10.1111/j.1744-6570.1999.tb00184.x/abstract</ref>

:*[[openness to experience]]<ref name="Judge, T.A. 2002"/><ref>Kickul, J., & Neuman, G. (2000). Emergence leadership behaviors: The function of personality and cognitive ability in determining teamwork performance and KSAs. Journal of Business and Psychology, 15, 27-51.</ref>

:*general [[self-efficacy]]<ref>Smith, J.A., & Foti, R.J. (1998). A pattern approach to the study of leader emergence. The Leadership Quarterly, 9, 147-160.</ref><ref name="Foti, R.J. 2007"/>

}}

While the trait theory of leadership has certainly regained popularity, its reemergence has not been accompanied by a corresponding increase in sophisticated conceptual frameworks.<ref name="Zaccaro, S. J. 2007">Zaccaro, S. J. (2007). Trait-based perspectives of leadership. American Psychologist, 62, 6-16.</ref>

Specifically, Zaccaro (2007)<ref name="Zaccaro, S. J. 2007"/> noted that trait theories still:

#focus on a small set of individual attributes such as Big Five personality traits, to the neglect of cognitive abilities, motives, values, social skills, expertise, and problem-solving skills;

#fail to consider patterns or integrations of multiple attributes;

#do not distinguish between those leader attributes that are generally not malleable over time and those that are shaped by, and bound to, situational influences;

#do not consider how stable leader attributes account for the behavioral diversity necessary for effective leadership.

===Attribute pattern approach===

Considering the criticisms of the trait theory outlined above, several researchers have begun to adopt a different perspective of leader individual differences—the leader attribute pattern approach.<ref name="Foti, R.J. 2007">Foti, R.J., & Hauenstein, N.M.A. (2007). Pattern and variable approaches in leadership emergence and effectiveness. Journal of Applied Psychology, 92, 347-355.</ref><ref>Zaccaro, S. J., Gulick, L.M.V. & Khare, V.P. (2008). Personality and leadership. In C. J. Hoyt, G. R. Goethals & D. R. Forsyth (Eds.), Leadership at the crossroads (Vol 1) (pp. 13-29). Westport, CT: Praeger.</ref><ref>Gershenoff, A. G., & Foti, R. J. (2003). Leader emergence and gender roles in all-female groups: A contextual examination. Small Group Research, 34, 170-196.</ref><ref name="Mumford, M. D. 2000">Mumford, M. D., Zaccaro, S. J., Harding, F. D., Jacobs, T. O., & Fleishman, E. A. (2000). Leadership skills for a changing world solving complex social problems. The Leadership Quarterly, 11, 11-35.</ref><ref>Smith, J.A., & Foti R.J. (1998). A pattern approach to the study of leader emergence, Leadership Quarterly, 9, 147-160.</ref> In contrast to the traditional approach, the leader attribute pattern approach is based on theorists' arguments that the influence of individual characteristics on outcomes is best understood by considering the person as an integrated totality rather than a summation of individual variables.<ref name="Mumford, M. D. 2000"/><ref>Magnusson, D. (1995). Holistic interactionism: A perspective for research on personality development. In L. A. Pervin & O. P. John (Eds.), Handbook of personality: Theory and research (pp. 219-247). New York: Guilford Press.</ref> In other words, the leader attribute pattern approach argues that integrated constellations or combinations of individual differences may explain substantial variance in both leader emergence and leader effectiveness beyond that explained by single attributes, or by additive combinations of multiple attributes.