Although the number of countries conducting large-scale assessments has increased significantly over the past two decades, this has not necessarily led to the effective use of learning assessment data in policy-making and planning. To better understand the reasons for this, the UNESCO International Institute for Educational Planning (IIEP) conducted a qualitative study in six sub-Saharan African countries that explored both how they use learning data in the education planning cycle and what influences their use. The study examines the use of data generated by national, regional, and international large-scale assessments as well as citizen-led assessments. When relevant, it also explores how it articulates with the use of other data, such as examination results. IIEP's research team together with researchers from the University of Namibia conducted an in-depth case study in Namibia, carrying out data collection in 2019. A number of interviews took place, as well as observations and focus group discussions with actors involved in the production and use of learning data at central and decentralized (i.e., regions) administrative levels. These were complemented by documentary analysis. Drawing from the research data, this policy brief explores the main lessons for national policy-makers and planners as well as international actors. [For the Information Sheet on Namibia, "Learning Assessments in Namibia," see ED617162.]