Primordial germ cells (PGCs) undergo epigenome reprogramming during their development from cells in the epiblast, migration and arrival at the embryonic gonad, but details of the dynamics of reprogramming during PGC development are not known. Now, Wolf Reik and colleagues report whole-genome bisulfite sequencing and RNA sequencing of mouse epiblast cells at embryonic day (E) 6.5, as well as of mouse PGCs at E9.5, E10.5, E11.5, E13.5 and E16.5 (Mol. Cell 48, 849–862, 2012). The authors found that there was extensive early global loss of DNA methylation between E6.5 and E9.5, but methylation was maintained at a select group of CpG islands in imprinted genes, X-linked genes and genes involved in meiosis and gamete generation. These genes then lost methylation once PGCs had entered the genital ridges. Analysis of patterns of change in methylation showed evidence of both passive and active demethylation. The authors used transcriptome data to define 12 clusters of transcripts with consistent expression changes during PGC development. These clusters included gene networks involved in pluripotency and meiosis. They also detected a burst of LINE1 retroelement transcription in female E16.5 PGCs. This work provides insights into the regulation of pluripotency and reprogramming in PGCs.