Many developmental processes involve transitions between different cell identities as cells differentiate or undergo reprogramming. Cell identity specifications are generally associated with the activation and suppression of specific sets of genes mediated by transcription factors. Therefore, transcriptional reporters, such as promoters of cell-type-specific genes, are broadly used as cell identity markers in developmental biology. In Arabidopsis (Arabidopsis thaliana), a collection of GAL4/UAS enhancer trap lines is an established standard for inferring cell identity. However, only a few of these enhancer trap lines have been molecularly characterized, which limits their potential. Here, we describe an approach for a detailed characterization of expression and mapping of T-DNA insert location of GAL4/UAS enhancer trap lines. Additionally, we demonstrate how the acquired information can be further used for the generation of novel cell-type-specific promoters as well as for genotyping of enhancer trap lines.