ABSTRACTIn support of investigating the effects of systematic archiving of authors' final peer‐reviewed, accepted manuscripts (green open access), PEER has developed a robust observatory infrastructure which has already successfully processed over 44,000 manuscripts. Technical challenges successfully overcome by the project include non‐uniformity of manuscript files and metadata formats, embargo management, and author authentication for repository deposit. Three areas of research investigating (i) author and reader attitudes and behaviours, (ii) article‐level usage at repositories and publisher platforms, and (iii) the economics of large‐scale archiving have been commissioned and are producing results. The baseline behavioural survey identified an increasing general awareness of open access, but a lower awareness of institutional and subject repositories. Perceptions were also found to vary depending on whether individuals were responding from an author or reader perspective. PEER itself has seen low uptake from authors when invited to self‐deposit into the project. Further results from all three research areas are due before the project ends in May 2012.