The great originality of this workshop resides in its aim of gathering experts from the so-called “spin physics” and “heavy-ion” communities who are interested by novel quarkonium related observables at colliders and fixed-target experiments. We also wish to gather senior researchers who contributed to the early experimental and theoretical studies with younger colleagues. As regards the scientific program, we plan to address issues related to the production of excited quarkonia, the associated production of quarkonia as well as polarisation and other correlation observables in quarkonium production. Both aspects related to polarised nucleon-nucleon collisions as well as heavy-ion collisions will be considered. Indeed, excited quarkonium states show an unexpected behaviour in the nuclear matter whereas the understanding of their production in pp collisions requires more observables to constrain the theory. One class of new observables is that of associated-quarkonium production which can provide extremely important information on the gluon TMDs as well as on the physics underlying double-parton scatterings both in nucleon-nucleon and heavy-ion collisions. The workshop will be a privileged moment for experts from Europe, the US and Asia to gather, exchange their know-how and discuss the progress of their most recent works.