Much progress has been made in understanding the molecular mechanisms of plant adaptation to heatstress. However, the great diversity of models and stress conditions, and the fact that analyses are oftenlimited to a small number of approaches, complicate the picture. We took advantage of a liquid culture sys-tem in which Arabidopsis seedlings are arrested in their development, thus avoiding interference withdevelopment and drought stress responses, to investigate through an integrative approach seedlings’global response to heat stress and acclimation. Seedlings perfectly tolerate a noxious heat shock (43°C)when subjected to a heat priming treatment at a lower temperature (38°C) the day before, displaying a ther-motolerance comparable to that previously observed for Arabidopsis. A major effect of the pre-treatmentwas to partially protect energy metabolism under heat shock and favor its subsequent rapid recovery, whichwas correlated with the survival of seedlings. Rapid recovery of actin cytoskeleton and mitochondrialdynamics were another landmark of heat shock tolerance. The omics confirmed the role of the ubiquitousheat shock response actors but also revealed specific or overlapping responses to priming, heat shock, andtheir combination. Since only a few components or functions of chloroplast and mitochondria werehighlighted in these analyses, the preservation and rapid recovery of their bioenergetic roles upon acuteheat stress do not require extensive remodeling of the organelles. Protection of these organelles is ratherintegrated into the overall heat shock response, thus allowing them to provide the energy required to elabo-rate other cellular responses toward acclimation.