Social skills are used mainly by the Expedition leader, Manager and Broker. They are used in interactions between the dwarves in your fortress as well as when talking with liaisons and merchants. Social skills are acquired at embarking, while performing the above administrative tasks or while attending parties.
The following list is based on the skills listed in the nobles screen when replacing a noble.
 List of Social Skills
 Miscellaneous conversational skills
It is unknown what specific circumstances make one or another of these useful; most of them are trained by parties, conversation between two or more idle dwarves, and trading. The latter fact implies that they are useful in trading, perhaps to get a better deal. They are also listed as mayor skills.
 Broker skills
- See Broker skills
All of the conversational skills listed above are trained by (and thus, presumably, used in) trading, possibly to get a better deal. It is believed that which skills are used may depend on the dwarf's personality. Note that the Appraiser skill, which is not a social skill, is also used in trading.
 Mayor Skills
Dwarves with these two skills can reduce the likelihood of tantrums by being complained at or cried on (which creates a happy thought for the other dwarf). These skills are also all listed as relevant for the manager.
 Gaining Social Skills
Dwarves train their social skills when idling in meeting areas or attending parties and they are standing near another dwarf. All social skills seem to train at roughly the same rate, though their personality traits will determine which skills they train - for example, a very self-conscious dwarf will not gain Comedian skill.