The County of Tripoli (1102–1289) was one of the Crusader states. It was founded in the Levant in the modern-day region of Tripoli, northern Lebanon and parts of western Syria. When the Frankish Crusaders, mostly southern French forces – captured the region in 1109, Bertrand of Toulouse became the first count of Tripoli as a vassal of King Baldwin I of Jerusalem. From that time on, the rule of the county was decided not strictly by inheritance but by factors such as military force (external and civil war), favour and negotiation. In 1289, the County of Tripoli fell to the Muslim Mamluks of Cairo under Sultan Qalawun, and the county was absorbed into Mamluk Sultanate.

Raymond IV of Toulouse was one of the wealthiest and most powerful of the crusaders. Even so, after the First Crusade, he had failed to secure any land holdings in the Near East. Meanwhile, the County of Edessa, the Kingdom of Jerusalem and the Principality of Antioch had been established. Tripoli was an important strategic goal as it linked the French in the south with the Normans in the north. It was a fertile and well populated area. In 1102, Raymond IV occupied Tortosa (now Tartus) and in 1103, he prepared, together with veterans of the 1101 crusade, to take Tripoli.

On a natural ridge, which he named "Mons Peregrinus" (French: Mont Pèlerin, English: Mount Pilgrim), 3 kilometres (1.9 mi) from Tripoli, Raymond IV (also known as Raymond de Saint-Gilles) began the construction of a large fortress, the Citadel of Tripoli (Arabic: قلعة طرابلس Qalʻat Ṭarābulus), formerly also known as the "Castle of Saint-Gilles" (Arabic: قلعة سان جيل Qalʻat Sān Jīl). Despite this new fortress and seasoned troops, Raymond IV's siege of Tripoli failed to secure the port. He died on 25 February 1105.

Count William of Cerdagne, Raymond IV's cousin and comrade, was supported by Tancred, Prince of Galilee, but his succession in the Tripoli campaign was challenged by Raymond IV's illegitimate son, Bertrand of Toulouse. Bertrand of Toulouse, who was supported by Baldwin I of Jerusalem, arrived in the Near East with a substantial army and a large Genoese fleet. In order to resolve the succession issue, Baldwin I created a partition treaty. It specified that William was to hold northern Tripoli and pay homage to Tancred, while Bertrand was to hold south Tripoli as a vassal of Baldwin. Under a united Christian onslaught, Tripoli fell on 12 July 1109, completing the Kingdom of Jerusalem. When William died of an arrow through the heart (some claim it was murder), Bertrand became the first count of Tripoli.

The extent of the County of Tripoli was determined in part by pre-existing Byzantine borders and in part by victory in battle, tempered by the demands of neighbouring crusader states. At its height, the county controlled the coastline from Maraclea in the north to Beirut in the south. Inland, the county's control extended to the Krac des Chevaliers fortress. The rich inland agricultural land of the Homs Gap was known as La Bocquée. The county was divided into 'lordships'; areas based roughly around its coastal ports. The count of Tripoli himself held the port of Tripoli and its surrounds. He also controlled the hostile region of Montferrand, now modern-day Bar'in, Syria, lying to the east. Approximately one quarter of the land seized around Tripoli was given to the Genoese as payment for military aid. The Genoese admiral Guglielmo Embriaco was awarded the city of Byblos.

The County of Tripoli was an autonomous state. Despite his contribution to its establishment, Baldwin I did not directly control the County of Tripoli. Nevertheless, the County of Tripoli owed fealty (allegiance) and homage (declarations of allegiance) to him, and he, in return, provided support to the county in times of trouble.

Although occupying a narrow coastal plain, the mountain range beyond was a natural defensive line for Tripoli. Several castle forts were built to defend the mountain passes. Muslim forces (Turk and Egyptian) attacked the County of Tripoli along its borders, especially those to the east. In 1137, Raymond II, the reigning count, lost control of Montferrand. The Muslim position strengthened when the Hashshashin (Nizari Ismailis) forces formed in the Nosairi mountains to the north. In 1144, in order to increase the county's defences, particularly against Zangi of Mosul, Raymond II gave the Knights Hospitaller large stretches of frontier land along the Buqai'ah plain. This included the castles of Krak des Chevaliers, Anaz, Tell Kalakh, Qalaat el Felis and Mardabech. In the 1150s, the defences were further strengthened by the presence of the Knights Templar at Tartus on the seashore.

In religious matters, the counties of the Kingdom of Jerusalem were expected to follow the lead of the Latin patriarch of Jerusalem. However, Count Pons had formed an alliance with Antioch, and acknowledged the Latin patriarch of Antioch. This was so even after a papal edict to the contrary.