I took the course also multiple times. Long story short, I don't recommend it. Here are the cliffnotes: * it's completely different from the McGuire breathing technique * with the DF (del ferro) method, it's not about breathing at all. It's about visualizing in your mind the up- and downwards motion of the diaphragm (in dutch: middenrif). As Great\_worry\_2981 pointed out, it's 100% a distraction method to stop focusing on anxiety, stuttering anticipation, negative reactions (and other triggers). * As Great\_worry\_2981 pointed out, we were not allowed to stutter. In my experience, the teacher told us, that if we stutter in step 1 (which according to the teacher is impossible) then we should go home and stop the 10-day program, and just quit the therapy. In my experience during the 10 days, no one stuttered in step 1, so in the end, no one quit the 10-day course. * My therapist in my stutter group, at the time, Patrick, completely recovered from stuttering with the del ferro method when he was 15 years old. It took him 1 or 2 years * The course itself is a 10-day course. So, you are required to sleep in Amsterdam for that amount of time. * We are video recorded 3x times to show the results * On the first day: In my stutter groups that I participated in, on the first day we were video recorded. We had to speak without the method in the first video and of course, everyone in my group stuttered * On the first day of therapy: The therapist teaches us the Del Ferro method step #1: put your hand in front of the diaphragm and move your hand up when breathing out (or speaking), and down when inhaling * Interestingly, it took around 10 minutes to explain step 1, and when everyone in the group tried the DF method, they did not stutter. In my experience, around 50 people who used the del ferro method step #1, did not stutter for those 10 days. The downside of the method is, that it can take 30 seconds to distract yourself from triggers, in other words, each phrase can take 30 seconds which, in reallife, was in my experience not doable. My family and classmates didn't accept it that I used this method so I never applied it at home or in University. * After a couple of days: if we master step #1, then we go to step #2, which is, stop using the hand movement, and instead, we visualize the hand movement in our head. This was a bit tricky for everyone, so when we stuttered even one time during step #2, we had to go back to step #1 and speak completely fluently for 1 or 2 days, and then we were allowed again to go to step 2. * Step #3 is to stop visualizing altogether and just speak normally, on auto-pilot like non-stutterers do. But in the 10-days, in my experience we only reached step #2, so I've never seen anyone reach step #3 (except for our teacher of course, who recovered from stuttering) * The teacher emphasizes many times that we are not allowed to speak like a robot with the DF method. In other words, we speak as natural, spontaneous and with intonation as much as possible. Additionally, we were not allowed to speak slower, in other words, we were required to speak in a normal pace as non-stutterers speak. * It's a 10-day program, daily from 9 to 16 at the therapy building. And then daily from 16PM to 20PM I believe, the stutter group (but without the teacher) were required to speak outside - so we spoke with strangers outside in the city center or central station to practice the DF method and desensitize fear and other triggers. * In step 1, we first speak with eyes closed - to avoid (visual) triggers, in step 2, we speak with eyes open * This therapy's main focus is on 'distracting ourselves from triggers'. What I miss in this therapy is a learning curve. So, future studies could improve the learning progress such as learning from the (relationship of the) perception of the stutter thoughts and feelings, building tolerance against triggers and removing its meaning. **In my opinion**: it may be more effective to focus on fluency laws over visualizing the diaphragm without reinforcing avoidance-behaviors. I consider 'distraction' also a form of avoidance