A pair of Breakthrough Technology papers in Plant Physiology discusses new tools to identify hydroxyproline-rich glycoproteins and insights into their evolution. Hydroxyproline-rich glycoproteins (HRGPs) are repeat-rich cell wall proteins that have been described as falling into three large families: arabinogalactan-proteins (AGPs), extensins (EXTs), and proline-rich proteins (PRPs). In the first paper (10.1104/pp.17.00294), Johnson et al. describe a motif and amino acid bias (MAAB) approach to classify HRGPs, which they now describe as falling into 23 sub-classes. Using these insights, Johnson et al. (10.1104/pp.17.00295) examine the phylogenetic distribution and evolution of HRGPs using data from the 1000 plant transcriptome project (www.onekp.com). They also describe the many remaining challenges to understand the contributions of these diverse proteins to cell wall structure and function. Plant Physiol.