New features of chloroplast gene expression are continually being discovered, particularly in the area of post-transcriptional RNA processing. RNA editing of chloroplast pre-mRNAs occurs in both monocotyledons and dicotyledons, and involves both initiator and internal codons. The view of introns as mobile genetic elements expands both with the identification of additional twintrons in Euglena chloroplast genes and with studies on the homing group I introns of Chlamydomonas.