European policy positions distance, online, and blended higher education as a route to widening participation, yet the mechanisms that make inclusion actionable remain dispersed across disconnected policy domains. This study examines how European-level policy and evidence texts conceptualise and operationalise inclusive distance higher education for four under-represented groups, namely women in STEM, migrants and refugees, learners with disabilities, and rural or remote learners. A qualitative document analysis of 40 sources, conducted as an actionability-oriented thematic synthesis, produced eleven mechanism clusters grouped into four interlocking themes: foundational enablers, inclusion-by-design learning conditions, targeted equity pathways, and governance, funding and safeguards. Governance, monitoring and cooperation appeared in all 40 sources, equality and values mainstreaming in 35 and accessibility and universal design in 15, counts reflecting documentary coverage rather than implementation. Inclusion becomes actionable not through any single measure, but through aligning these themes into a chain of actionability whose effect is relational and most fragile at the governance link. Policy attention across the four groups is uneven, being operationalised most robustly where it is measurable and least where it is relational. The study offers a transferable framework for understanding inclusion as a coordinated accomplishment across policy layers.