Grassley, a prolific tweeter known for his creative use of abbreviations in order to fit into Twitter's 140 characters, has sometimes been accused of tweeting in an unknown language, but typically tweets in English.
"The pope's presence on Twitter is a concrete expression of his conviction that the Church must be present in the digital arena," the Vatican said in a statement.
The pope's official Twitter account follows the Vatican's cautious acceptance of social media. The Vatican has called social networks such as Twitter "a great opportunity" but cautioned that users should not allow the virtual world to make them "less present" in the real one.
The account name was selected to highlight the pope's desire to build bridges to "everyone," including those online, according to Vatican representatives at the press conference.
The pope's first tweets next week will be answers to questions submitted with the hashtag #askpontifex, according to Reuters.