Sucking a thumb or carrying a blankie around is a need for security. Incentive charts, telling him it is for bed-time only and having him pull it out of his mouth. Which may be ALOT!! Praising him for the times you DON'T see it in his mouth is a key. Children need that positive attention too. Giving him alot of time and attention and LOVE another key. So often we let the children play video games, watch tv but what they really need is our time, talking with them, reading to them...he may just be one of those that needs that EXTRA time. I'm sure you are a wonderful mother, every child is different, finding out his love languages (Love languages by Gary Smally) will help fill his 'love tank'. Blessings, A.