Yes, you can still enroll! Many of our self-paced courses can be joined months after the start date.
For our instructor-paced courses, you may join late but you will not be able to turn in any assignments or exams that are past due. If it is early in the course, you might still be able to complete enough assignments and exams to earn a certificate. I'd recommend enrolling and taking a look at the course info and course syllabus to learn more. You can also simply audit the course, and you can participate as much or as little as you would like to — there is no penalty for not completing assignments in courses that you audit.
You are also welcome to wait and sign up for the course when it is offered again. You will receive updates regarding new and repeated courses if you are signed up at edX.org.