Insights into the signal transduction of the phytohormone abscisic acid (ABA) have unfolded dramatically in the past few years and reveal an unanticipated complexity. Knockout lines and RNA-interference technology, together with protein interaction analyses, have been used to identify many of the cellular components that regulate or modulate ABA responses. ABA signaling is characterized by a plethora of intracellular messengers. This may reflect the function of ABA in integrating several stress responses and antagonizing pathways via cross-talk, but it hampers the establishment of a unifying concept. Transcriptome analyses have unraveled more than a thousand genes that are differentially regulated by ABA, and these ABA-mediated changes in gene expression translate to major changes in proteome expression. ABA-induced mechanisms that re-adjust cellular protein expression are just surfacing. ABA-response-specific transcription factors have a well-established function in that process and, recently, it has also become clear that phytohormone signaling enforces a sophisticated interference with protein expression at the posttranscriptional level. This interference includes both targeted proteolysis and the regulation of the translation of specific mRNAs by RNA-binding proteins.