No not necessarily. Your credit score is determined by your history of paying back accounts from lenders. While you don't need a credit card they tend to be how most people build credit. To get a good score without a card (assuming you're applying for a loan or some kind of financing) you'll need either a cosigner, someone who has credit and is willing to put it on the line for you and their credit becomes yours basically but they take most of the risk and penalties if you default. Another option is a loan which you pay back every month ON TIME in order to build a good score over time.