There were six major officers of the kingdom of Jerusalem: the constable, the marshal, the seneschal, the chamberlain (which were known as the "Grand Offices"), the butler and the chancellor. At certain times there were also bailiffs, viscounts and castellans.
Essentially these offices developed from the typical officials that existed in northern France in the 11th century, the homeland of the first kings of Jerusalem. The offices continued to develop in France and England, but in Jerusalem they tended to develop more slowly or not at all, taking on different roles than their European counterparts.
The lists given below are incomplete, as the specific names and dates of the officers are sometimes unknown. After the fall of the Kingdom of Jerusalem, the offices were sometimes awarded as honors by the kings of Cyprus and Jerusalem.
The constable commanded the army, paid mercenaries and judged legal cases pertaining to the military. He was the most important officer in the kingdom, due to the almost constant state of warfare that existed between the Christian and Muslim states. The constable was officially the second-in-command of the army, in which he exercised police authority and commanded a division twice as large as all others. In addition, constables also determined the boundaries and borders of the kingdom. During the coronation the constable would hold the king's horse.
The marshal was next-in-command (and, apparently, a literal vassal) to the constable. He led the mercenaries and was in charge of the army's horses, and distributed the spoils of a victorious battle. On coronation day the marshal would assist the constable.
The office of seneschal in Jerusalem never achieved the prominence of its European counterparts but was important nonetheless. The seneschal administered the coronation ceremony, oversaw the Haute Cour in the king's absence, administered royal castles, and managed the royal finances and revenue. The seneschal's power was over only viscounts and not castellans, and the constable was still superior to the seneschal due in part to the kingdom's constant state of war. During coronations the seneschal would hold the royal sceptre and oversee the coronation feast.