This paper contrasts the intonation of Buenos Aires Spanish with classic Spanish according to the variables of gender and age. The corpus contains declarative, wh-question and exclamatory sentences, uttered in a repetition task by 72 native speakers, 36 males/36 females equally divided into three age – groups (5-8; 18-50; 51-75). The data were analyzed using the Autosegmental¬¬-Metrical model with the ToBI system adopted for Argentine Spanish. The results were explained according to the principle that language represents a compromise in the struggle to achieve maximum communication through minimal effort (Diver, 1979, 1995; Davis 1984/1987; Tobin, 1997). The data show an inverse proportion between the difficulty of the sentence and the range of prosodic variation. The most simple declarative sentence has the largest variation for both gender and age. In the most difficult wh- questions, speakers prefer marked patterns with variation in gender and age. In the less difficult exclamatory sentence, there were minor differences for both gender and age. Our data indicate that: (1) females of all ages consistently prefer marked forms; (2) male children tend to follow adult female speakers; (3) adult males have more random patterns and (4) adults (18-50) of both genders have the most variation in wh-questions.