This is a common question. The short answer is YES, you must. In our early days, we used to allow ourselves to be persuaded to permit some psychologists and psychiatrists to skip this course, and we were sorry we did.
Taking psychology courses does not necessarily expose one to the attachment-based developmental approach. And even if one has been exposed, the Level One Intensive is necessary as it lays out the theory in a logical and coherent way, enabling one to master the model as well as set the stage for universal application. Also, there is the language, which is pivotal in the case of this articulation of the paradigm. Dr. Neufeld attempts to use language that does not divide expert from non-expert and that resonates with intuition.
Even if one has taken numerous courses from Dr. Neufeld himself, if interested in further study or in being a resource to others, the Level One Intensive: Making Sense of Kids, is foundational. We have never heard anyone say, no matter how educated in psychology. that taking the Intensive One was a waste of time. On the contrary, we have only received feedback that once they had taken this, they realized why it was so necessary.