Imagine that you see an ad online for a used computer. You respond to the advertisement and after a few emails back and forth about the computer, you decide you want to buy it. You want to enter into a contract with the seller for the purchase of their computer. You are 30 years old, and the other person is just 17 years old. So the question is, 'Can this person enter the contract at age 17?' In other words, 'Does the 17 year old have the capacity to enter into the contract as a minor?'These questions relate to what is known as contractual capacity. Contractual capacity is the ability of a person to enter into a contract. There are certain classes of people that are typically incapable of entering a contract, or lacking contractual capacity.