Yes and no. If you happen to hear a pop or crack while under controlled movement such as stretching or just simply turning your neck, then that is ok. Cracking your own neck becomes a problem if it becomes a habit and you feel like you need to self-adjust yourself multiple times a day or even if you have to do it daily. The reason this is a problem is that your body is trying to feel more comfortable, self-adjusting can actually cause more harm than good because of the forced rotation on one's own neck. Proper chiropractic adjustments do not have a lot of forced rotation. Forced rotation can eventually lead to degenerative changes and arthritis. In fact, those under chiropractic care report a decrease in the urge to self-adjust or crack their own neck. Restoring the proper range of motion in the spine will provide that kind of relief.