Flow cytometry, and the accompanying technology of cell sorting, represents an established and valuable experimental platform for the analysis of cellular populations. Applications involving higher plants, which started to emerge around 30 years ago, are now widely employed both to provide unique information regarding fundamental questions in basic and applied bioscience and to advance agricultural productivity in practical ways. Further developments of this platform are being actively pursued, promising additional advances in our understanding of the interactions of cells within the complex tissues and organs. Higher plants offer unique challenges in terms of flow cytometric analysis, first since their organs and tissues are, almost without exception, three-dimensional assemblies of different cell types and second that their individual cells are generally larger than those of mammals. This chapter focuses on the use of flow cytometry and cell sorting with the model species Arabidopsis thaliana, in particular addressing (1) fluorescence in vivo labeling of specific cell types, (2) fluorescence-activated sorting of protoplasts and nuclei, and (3) transcriptome analyses using sorted protoplasts and nuclei.