Scottish Clans also contained septs or branches, which were founded when powerful or prominent clansmen established their own important families. Clans often had many septs that were often related through marriage. During difficult times, the families sought to ally themselves with larger more powerful clans for protection from enemies and other feuding clans alike. This practice, which often included paying homage to the Clan Chief at important events was effective in building respect, devotion and familiarity between different families within the same clan.

Nowadays, this relationship is all but lost, but today septs often wear that clan tartan and proudly display their clan's badge.

Some septs became so powerful that they later became clans in their own right.

In Ireland, septs were the Irish equivalent to the Scottish Clan in political and economic stature.