You can contribute to a campaign via PayPal, even if you do not have a PayPal account.  Use your credit card to "Pay as a Guest" without signing in:

1.  When you get to the PayPal screen, you'll see up top "Choose a Way to Pay"
2.  Select the second option: "Pay with a debit or credit card"
3.  Complete the form - PayPal accepts Visa, MasterCard, Discover, and American Express
4.  Deselect the checkbox that says: "Save this information with a PayPal account"
5.  Click "Review and Continue" to continue with a payment using a credit card
6.  Click on the "Continue Without Logging In" link

Why is PayPal the only option to contribute?

Campaign owners can elect to use PayPal as their only method of collecting funds.  If you only see the option to pay via PayPal, this is intentionally set by the campaign owner.  

Is there a limit to how much I can contribute as a guest on PayPal?

PayPal implements certain limits on the amount of money that you can send. If you're paying as a guest in PayPal, you will not be able to contribute more than $500. You will also only be able to use PayPal's guest checkout process up to 15 times with a total spending limit of $4,000. Once you reach PayPal's maximum, you will be prompted to upgrade to a full PayPal account. If you're paying with your PayPal account and receive an error message after attempting to contribute claiming that you exceeded your spending limit, we recommend contacting PayPal Support directly.

For campaigns in a currency other than USD, the guest checkout limits are the local currency equivalent of $500 USD per-transaction and $4,000 USD total. If you have more questions about localized restrictions, we recommend that you contact PayPal directly. You can find a list of localized PayPal sites here: https://www.paypal.com/worldwide/

Related Links:

If you would like to contribute using another payment method, please visit:  How to Contribute to a Campaign

For more information about the security of your transaction, please visit:  Online Security