Yes, you can. Many self-paced courses can be joined months after the start date. For instructor-paced courses, you may join late but you will not be able to turn in any assignments or exams that were due before you enrolled. If it is early in the course, you might still be able to complete enough assignments and exams to earn a certificate. You can find out more on the course page. 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. Many courses are repeated, so you can also wait and sign up for the course when it is offered again.