Trial court judges are often referred to as the workhorses of the judicial system. This is unsurprising given that millions of civil and criminal cases are filed and resolved in U.S. state and federal trial courts each year. Very few of these cases ever reach appellate courts, meaning that trial courts are often the first and only court with which people directly interact. At the same time, trial courts can make local and national policy, both in individual cases and in the aggregate. This important role of trial courts and their actors has not gone unnoticed by scholars across social science disciplines. One can consider trial courts in a broad sense by tracking the historical developments that led to the trial courts in the United States. As caseloads have increased, trial courts—particularly those with specialized jurisdictions—have been created out of necessity. State trial courts feature variation in their judicial selection methods, including elections and appointments. At the federal level, increased polarization has led to contentious partisan confirmation battles for federal trial court judges. Trials are a rare occurrence, with plea agreements and settlements being the most frequent methods of resolving cases. To understand trial court actor behavior, it is important to remember that state and federal trial courts sit at the bottom of their judicial hierarchies. The preferences of their hierarchical superiors, along with the presence of high trial court caseloads and the rarity of trials, rein in judges’ discretion and the potential effects of their personal characteristics and attitudes. Because of these judge constraints, actors such as prosecutors, defense attorneys, and juries play a significant role in trial court outcomes. As the literature reveals, the “repeat players” in trial courts hold significant advantages over less experienced litigants and attorneys that affect their likelihood of gaining favorable outcomes, among other things. Race and gender of these actors can have significant effects on behavior in certain types of cases. There are many hurdles that remain for scholars seeking to study trial courts. For example, state trial courts, in particular, continue to be difficult to study empirically. This is due largely to a lack of data availability. Relatedly, scholars must continue to strive to find ways to study trial court outcomes and events that do not lead to published opinions—for example settlements, plea bargains, prosecutorial declinations, and many decided motions. Each of these involves important decisions and outcomes that affect parties and may be affected by judges and lawyers.