Depending on how long you have been married and when your spouse earned his or her retirement, you may be entitled to a share in your divorce. An individual may even have more than one retirement plan - (due to employment with the government/armed services, or multiple positions during working career).
Some people know little to nothing about their spouse's retirement plan and may not even know whether or not their spouse has one. Some people tend to be very private or secretive about their finances, even with their spouse.
However, there are ways to discover this information during the time that the divorce is pending. You and your spouse will both be under court orders to be honest and reveal this financial information. Some information will be exchanged automatically between the two attorneys.
In addition, there may be discovery in the form of written requests, deposition, or subpoenaed information. Information can be exchanged informally between the two attorneys and can also be exchanged during mediation process. There may also be hearings in the courtroom about these and other issues.
Of course the best way to have this information is by being informed in the first place or by exchanging information during the divorce in a cooperative way. This takes less time and costs everyone less money. However, if you are one of the unfortunate people who has a spouse that absolutely refuses to share this information be aware that the legal process of divorce has procedures in place to help you can get information that you are entitled to know.