The paper looks at challenges related to the ideas of integration and knowledge systems in extra-academic transdisciplinarity. Philosophers of science are only starting to pay attention to the increasingly common practice of introducing extra-academic perspectives or engaging extra-academic parties in academic knowledge production. So far the rather scant philosophical discussion on the subject has mainly concentrated on the question whether such engagement is beneficial in science or not. Meanwhile, there is quite a large and growing literature on extra-academic TD, mostly (...) authored by non-philosophers, seeking to develop TD research practices. We examine this literature in the light of recent discussions in pluralist philosophies of science. Some philosophical pluralists see the increase of extra-academic collaboration and participation in science as a potentially positive development. However, certain views promoted in the non-philosophical literature on extra-academic TD appear problematic in the light of the pluralistic discussions. For instance, the literature on TD appears to be overly optimistic with regard to integration, and the notion of knowledge systems used in it is problematic. We believe it would be worthwhile for scientific pluralists sympathetic to the aims of TD to look more closely into the complex settings in which extra-academic collaboration and participation happens in actual TD projects, and to offer constructive criticisms, exploiting insights developed within pluralist philosophy of science. (shrink)