It falls in the general category of "fornication" -- sex outside marriage. There are quite a few references, although I left my concordance in my other pants.

Premarital sex is NOT forbidden in the Bible. Fornication does NOT mean premarital sex.

Here are some Scriptures that teach about premarital sex: Exodus 22:16-17: An man had to marry the woman with whom he had premarital sex, if the father approved of the marriage, or pay a high price. Deuteronomy 22:13-21: Premarital sex is viewed as evil and a disgraceful thing. Proverbs 5:15-21: A man is to be a virgin when he takes his wife. In addition to these Scriptures, there are over 30 other verses in the Old Testament speaking about a "virgin" or "virgins." Virginity was highly cherished as the standard for God's people. In the New Testament we don't have verses describing the act of premarital sex and its consequences like we do in Exodus or Deuteronomy. It is clear, however, that virginity is still the standard for unmarried Christians and that sex outside the context of marriage is still considered sin. 1 Corinthians 7:7:28,34,36-38: Virginity is assumed for unmarried women just as in the Old Testament. Virginity is still the standard for God's people in the New Covenant. 1 Corinthians 6:16-18: Sexual intimacy "unites" you with your spouse. Outside of marriage this is called "sexual immorality." 1 Corinthians 7:1-2: Marriage is recommended avoid sexual immorality. 1 Corinthians 7:8-9: Premarital sex isn't an option for dealing with lust. Marriage is once again recommended avoid sexual immorality. Ephesians 5:31: Paul is affirming the Old Testament standard of uniting in flesh only with your spouse. One fleshness is to happen when a man is "united to his wife." 1 Thessalonians 4:2-8: "Acquire a wife in a way that is holy and honorable" or you are in sexual immorality. Sexual sin harms others besides those who engage in it. Premarital sex "cheats" the future spouse by robbing him or her of the virginity that ought to be brought to marriage. Hebrews 13:4: It is a pure marriage bed or you are an "adulterer" or "sexually immoral." 1 Timothy 5:2: As a Christian man, if you are not married to her, then she is your sister whom you must treat "with absolute purity." 2 Corinthians 11:2: Although this passage is talking about Christ and His people, it uses the analogy of a Christian man receiving his bride "as a pure virgin." Virginity was the ideal. Premarital sex was viewed as sexual immorality - just as in the Old Testament. With love in Christ.

Premarital sex IS Forbidden!!!! I can't believe how some people don't understand why it is sooo wrong! It's pretty sad where the world has come to. I know very few people who have remained virgins. I don't understand why it is so hard. I am 23 and I am still a virgin and I plan to be till I am married. It is a pretty simple to understand why pre-marital sex is WRONG. When someone cheats on their husband or wife by sleeping with someone else, it is considered Adultery, because you are having sex with someone other than your spouse. Well, its the same thing with pre-marital sex people!! When you have sex before you are married, you are having sex with someone other than your spouse! You are cheating on your FUTURE spouse! Come on people, it's not a hard concept to understand!! We all need to wake up and stop thinking that we can just go about our lives and do whatever we want, and just commit any kind of sin. I can't believe people think they can just go to Heaven with no fear of the sins they have commited. Every single person has to stand before God and has to explain their actions. We all have to pay for our sins. We must earn a place in Heaven. You don't just get a free ticket!