Capricorns are known to get along well with others whose sun signs are Taurus, Virgo, and Scorpio. Capricorns also typically get along with other Capricorns.
Compatibility between Taurus and Capricorn comes from a deep respect for each others personality and both signs benefit by combining their different strengths. Virgos and Capricorns get along well due to the combination of Virgo's strong mental focus and Capricorn's developed sense of discipline. Those who have their sun sign in Scorpio are harmonious with Capricorn because Scorpios have a protective nature and Capricorns have a pronounced longing to be the object of someone's desire and protectiveness.
Capricorns are known to be loyal, dedicated and disciplined. They match best with other signs that are dependable, stable and able to understand Capricorn's tendency to be introverted. This is one reason why Capricorns are one of the few signs that actually match well with their same sign.
There is a possibility that Capricorns are also compatible with Libras. If the Libra in question can be self-motivated it would augur well for a relationship between the two signs. Leo, Aries, Aquarius and Pisces are all poor matches for Capricorn due to major clashing personality traits. Capricorn is best suited with signs that are similar in temperament.