This paper examines the use of the two allomorphs of the Indonesian word for yes, ya and iya, in Indonesian conversational data. Both are frequently used responsively, as an affirmative marker or a conversational continuer. They can also be used as a tag question to initiate an exchange or make a request that has a low social cost, and as a discourse marker, although iya is relatively rarely found in the latter two functions. As a discourse marker ya has a number of different functions, occurring in repairs, in conclusion drawing, in echoing, and most frequently as a means of building solidarity through the creation of fictive common ground. The high frequency of this type of usage in Indonesian conversation can be seen as a reflection of Indonesian cultural values, which place a premium on maintaining the appearance of cooperative behavior.