Carol Gilligan is the author of the book "In a Different Voice: Psychological Theory and Women's Development" (1982) and is most famous for challenging Kohlberg's Conception of Morality and it's basis in research conducted primarily on men. She explores whether moral constructions differ for men and women and argues that female moral development centers more on the morality of care than the morality of justice.

Gilligan argues that there is not any single unifying system of morality for men and women. She notes that for some individuals (particularly women) morality is based primarily on caring and responsibility, and the idea that acting justly requires nonviolence. Meanwhile, she notes that for others (particularly men) morality centers around justice and rights, which can only be maintained by preserving equality. Thus, these two different moralities require unique actions for their followers to be considered truly just. For example, in care-based morality you do the right thing by never avoiding helping someone in need, while justice-based morality simply commands it's followers to never treat someone unfairly or unequally. These two differing moral orientations frequently correlate to gender differences as well along these lines...

Care-based Morality:

• Emphasizes interconnectedness and universality.
• Acting justly means avoiding violence and helping those in need.
  
• Thought to be more common in girls because of their connections to their mothers.
• Because girls remain connected to their mothers they are less inclined to worry about issues of fairness.

Justice-based Morality:

• Views the world as being composed of autonomous individuals who interact with one another.
• Acting justly means avoiding inequality.
  
• Thought to be more common in boys because of their need to differentiate between themselves and their mothers.
• Because they are separated from their mothers boys become more concerned with the concept of inequality.

Gilligan was also particularly interested in developing an alternative stage theory of moral development after she noticed that the work of her mentor, Lawrence Kohlberg, always indicated that women were less morally developed than men. While men were more likely to recieve high scores on Kohlberg's stages of Moral Development, she realized that these differences emerged primarily out of an emphasis on the justice-based morality which women did not seem to share.

Gilligan concluded women were not in fact deficient moral thinkers, but rather thought differently than men about issues of morality. She argued that women's moral development was based on the interconnections between people and about caring for others, rather than the self-preservational justice-oriented view offered by her predacessor. In particular, Gilligan created the following hierarchy to describe the steps of her ethics of care as a comparison to Kohlberg's original stages of moral development...

Gilligan's Stages of the Ethic of Care
Approximate Age Range	Stage	Goal
not listed	Preconventional	Goal is individual survival
Transition is from selfishness -- to -- responsibility to others
not listed	Conventional	Self sacrifice is goodness
Transition is from goodness -- to -- truth that she is a person too
maybe never	Postconventional	Principle of nonviolence: do not hurt others or self

References

Gilligan, C. (1982). In a different voice: Psychological theory and women's development. Harvard University Press: Cambridge.