One of the most well-known behavioral theories is Douglas McGregor's Theory X and Y.  While not a leadership theory per se, it provides an insight into leadership styles. A subscriber to Theory X reflects a manager's negative view of subordinates, believing subordinates dislike work, avoid responsibility, and lack ambition . A subscriber to Theory Y believes that subordinates seek work that is physically and mentally rewarding and want to control their destinies. Naturally, a manager who subscribes to Theory X will apply the "stick" to motivate subordinates , while one who subscribes to the latter will apply the " carrot ."
Rensis Likert conducted research at the University of Michigan to determine the style that best results in high-producing groups. He looked at two styles: employee centered and job centered. An employee-centered style stresses the human side, a style that emphasizes communication, trust, and goal setting. A job-centered style is more task oriented, with emphasis on meeting production standards and supervising closely. 
Likert notes that the employee-centered style results in high-producing groups. These groups have less absenteeism and turnover in addition to high productivity. Overall, these groups involved general, not close, supervision.
Likert also provides a continuum that identifies four leadership styles: Systems 1, 2, 3, and 4. System 1 is very task oriented, when management has a negative orientation, such as the use of threats and punishment . System 2 exists when management exhibits very modest confidence in subordinates, but decision making still rests at the top. System 3 exists when management exhibits a considerable trust and confidence in subordinates and allows for some specific decision making at the lower levels. System 4 occurs when management has complete trust and confidence in subordinates, allowing group decision making and building supportive relationships. The implication of Likert's work is that System 4 is the best approach.
Another well-known behavioral theory is Robert Blake and Anne McCanse's Managerial Grid. The basic idea is that five managerial styles exist that are created by considering two major dimensions or concerns for production and people. The concern for production focuses on performance, results, and profits. The concern for people focuses on relationships and motivational factors. The grid formed by the two dimensions creates five management styles: Impoverished, Authority Compliance, Middle of the Road, Country Club, and Team. An Impoverished manager displays little concern for production and people; he or she avoids getting involved, and does the minimum. An Authority Compliance, or task, manager emphasizes efficiency over people issues. His or her concern is to achieve results through control, even domination. A Middle of the Road manager focuses on balancing both concerns. The words "adequacy" and "reasonableness" pertain to this managerial style. A manager exhibiting the Country Club style places people over production. He or she emphasizes satisfying relationships among people; the words "pleasing" and "approval" are often associated with this managerial style. With the Team management style, a manager builds commitment to production by coordinating and integrating work to achieve results. The words " interdependence " and "respect" are often associated with this style.
Unlike other managerial styles indicating that the preferred style depends on the situation, Blake and McCanse believe the best managerial style is team management. Here the focus is on achieving results without sacrificing people as is the case with the Authority Compliance style or catering to people attributed to the Country Club style. 
Ohio State University conducted studies of leadership. The Ohio State studies considered two dimensions of leadership: initiating structure and consideration. Initiating structure dealt with formality towards organization, communication, and procedures; consideration dealt with people issues like trust, respect, and feelings. Using a questionnaire, the study found that the two dimensions were distinct but not mutually exclusive, that is, a "high" in one meant a "low" in the other. The study resulted in a quadrant that reflected the different relationships between the dimensions: low structure and low consideration, high structure and low consideration, high consideration and low structure, and high structure and high consideration.
 James H. Donnelly, James L. Gibson, and John M. Ivancevich, Fundamentals of Management , Business Publications, Inc., Piano, TX 1981, pp. 218 “219.
 Paul Hersey and Kenneth H. Blanchard, Management of Organizational Behavior , Prentice Hall, Englewood Cliffs, NJ, 1993, pp. 300 “301, 338 “340.
 Robert R. Blake and Anne A. McCanse, Leadership Dilemmas ” Grid Solutions , Gulf, Houston, TX, 1991, pp. 25 “35.