King Alexander II ruled Scotland for 35 years. His relationship with the neighbor to the south, England, was contentious at times and friendly at times. Alexander is also the first Scottish monarch known to have a proto-Parliament.

The only son of William the Lion and Ermengarde of Beaumont, Alexander succeeded his father as king in 1214. The very next year, he put down one revolt, in Scotland, and joined another one, in England. Alexander led an army into England to support the barons who had revolted against King John.

The First Barons War had begun after John had renounced his support for Magna Carta. The two sides faced off, and the barons who rebelled against the king and offered their allegiance instead to Prince Louis of France. By September 1216, Alexander and the Scottish army had marched the length of England arrived at Dover, to meet up with the French force. John died the next month, and the barons threw their support behind John's son, who became King Henry III. This alliance had the support of the pope as well, and the French and Scottish armies returned home.

The alliance between England and Scotland grew stronger. Henry signed the Treaty of Kingston with both Alexander and Louis in 1217, and Alexander married Henry's sister Joan in 1221. The two monarchs ironed out a dispute a decade later without coming to blows. The resulting Treaty of York defined the border between the two kingdoms, from the Solway Firth to the River Tweed. A late attempt by Henry to invade was met with an accompanying show of strength from Alexander, and no battle ensued.

Alexander had a different outcome with a later struggle. In 1249, he set about trying to bring the Outer Hebrides, or Western Isles, into the fold. They were at the time still beholden to Norway. Alexander set out with an army to take the isles by conquest and died during the journey, on the Isle of Kerrara.

Alexander's wife, Joan, had died in 1238. The couple had had no children. Alexander, wanting an heir, married again, the following year. His second wife was Marie de Coucy. Their son, born in 1241, became King Alexander III.

The earliest mention of a Scottish Parliament is from 1235, when Alexander II was king. A surviving letter describes a meeting of the king's great council at Kirkliston, on the outskirts of Edinburgh, as a "colloquium." This group of advisors had a political and a judicial role.