An electrical connector, adapted for electrically connecting an integrated circuit package, comprises a plurality of contacts, a plurality of solder balls disposed on tails of the contacts and an insulative housing. The insulative housing defines a plurality of passageways receiving the contacts. Each contact has a retaining portion, an elastic arm and a soldering portion. The contacts positioned in two adjacent rows of passageways are arranged staggered in a back to back manner. Such arrangement of the contacts of the electrical connector allows much more contacts to be put in the insulative housing.