Eukaryotic translation elongation factor 1A (eEF1A) is an essential, highly conserved and abundant protein required for protein synthesis in all eukaryotes. eEF1A is also highly post-translationally modified – it is modified by dozens of phosphorylation sites and methylated by more independent methyltransferases than any other protein [1]. However, it remains unknown whether any eEF1A post-translational modifications engage in crosstalk. Here we show that phosphorylation of eEF1A inhibits its nearby methylation. Using affinity enrichment of Saccharomyces cerevisiae eEF1A followed by phosphopeptide enrichment and LC-MS/MS, we find that eEF1A is co-modified by phosphorylation at serine 314 and methylation at lysine 316. We show that S314-phosphorylated eEF1A has a significantly lower level of K316 methylation than unphosphorylated eEF1A, indicating that phosphorylation may inhibit nearby methylation. To show this directly, we test the effect of phospho-mimic (aspartate) and phospho-null (alanine) mutations on eEF1A methylation both in vivo and in vitro. We show that an S314D mutation reduces K316 methylation levels in vivo, while an S314A mutation does not. Similarly, an S314D mutation significantly reduces the capacity of eEF1A K316 to be in vitro methylated by elongation factor methyltransferase 4 (Efm4), the K316-specific methyltransferase. Structural modelling of the eEF1A-Efm4 complex with AlphaFold2 shows that S314 forms a hydrogen bond with a conserved asparagine residue in Efm4, suggesting that phosphorylation may decrease Efm4 affinity for eEF1A by disrupting this interaction. Altogether, our results show that phosphorylation of eEF1A S314 inhibits nearby methylation at K316 by its sole methyltransferase. This is the first instance of PTM crosstalk discovered on this important protein, suggesting that eEF1A is subject to layered regulation through crosstalk of its many PTMs.