What scope of data are you talking about? You’re not being hugely specify but there are ways to retrieve Tweets via both the REST or Streaming APIs. What are you trying to achieve?
You can search for a term and specify English as the language and that will return you a result set of Tweets up to 7 days old. Tweets from protected user accounts will be excluded, the index is not complete, and you do have to specify a search query, but this works.
You can retrieve a user’s timeline.
The Streaming API returns up to 1% of the complete firehose of Tweets based on a filter term.