Pro se legal representation (/ˌproʊ ˈsiː/ or /ˌproʊ ˈseɪ/) means to argue on one's own behalf in a legal proceeding, as a defendant or plaintiff in civil cases, or a defendant in criminal cases, rather than have representation from counsel or an attorney.

The term pro se comes from Latin pro se, meaning "for oneself" or "on behalf of themselves". This status is sometimes known as in propria persona (abbreviated to "pro per"). In England and Wales the comparable status is that of "litigant in person". In Australia and Canada, the term is self-represented litigant (SRL).

According to the National Center for State Courts in the United States, as of 2006 pro se litigants had become more common in both state courts and federal courts. This increase is due to a number of factors, including a fall in funding for federal legal aid, an increase in provision of limited legal assistance, and increase in divorce rates. Estimates of the pro se rate in family law cases overall averaged 67% in California, 73% in Florida's large counties, and 70% in some Wisconsin counties. In San Diego, for example, the number of divorce filings involving at least one pro se litigant rose from 46% in 1992 to 77% in 2000, in Florida from 66% in 1999 to 73% in 2001. California reports in 2001 that over 50% of family matters filings in custody and visitation are by pro se litigants. In the U.S. Federal Court system for the year 2013 approximately 27% of civil actions, 92% of prisoner petitions and 11% of non-prisoner petitions were filed by pro se litigants. Defendants in political trials tend to participate in the proceedings more than defendants in non-political cases, as they may have greater ability to depart from courtroom norms to speak to political and moral issues.

In Faretta v. California, the Supreme Court of the United States stated:

In the federal courts, the right of self-representation has been protected by statute since the beginnings of our Nation. Section 35 of the Judiciary Act of 1789, 1 Stat. 73, 92, enacted by the First Congress and signed by President Washington one day before the Sixth Amendment was proposed, provided that "in all the courts of the United States, the parties may plead and manage their own causes personally or by the assistance of counsel."

The Court's opinion went on to hold that criminal defendants, in state courts, have a constitutional right to refuse counsel and represent themselves.

However, the right to represent oneself is not absolute. Courts have the authority and duty to determine whether a particular individual is capable of representing himself or herself. In Godinez v. Moran, the Supreme Court found being competent to stand trial is equivalent to being competent to plead guilty, which further meant being competent to waive legal representation. The later Indiana v. Edwards decision allows a court to inquire into the individual's lucidity and mental capacity, and sets competency to represent oneself as distinct from one's competency to stand trial.

Martinez v. Court of Appeal of California determined that an appellant who is the defendant in a criminal case cannot refuse the assistance of counsel on direct appeal whereas Faretta v. California allows criminal defendants to proceed pro se for their own defense.