We provide a protocol to enable the mass spectrometry-based characterization of proteins in identified cell lineages in Xenopus laevis (frog) embryos. The experimental workflow leverages reproducible cell-fate maps and established technologies from developmental biology to identify, fluorescently label, track, and analyze cells and their progenies from this important biological model of vertebrate development. Proteins are identified and quantified via bottom-up proteomics. Microanalytical capillary electrophoresis or nanoflow liquid chromatography (nanoLC) are used to separate peptides, and electrospray ionization (ESI) high-resolution mass spectrometry (HRMS) are employed for detection.