The decision by a cell to enter a round of growth and division must be intimately coordinated with nutrient availability and its metabolic state. These metabolic and nutritional requirements, and the mechanisms by which they induce cell growth and proliferation, remain poorly understood. Herein, we report that acetyl-CoA is the downstream metabolite of carbon sources that represents a critical metabolic signal for growth and proliferation. Upon entry into growth, intracellular acetyl-CoA levels increase substantially and consequently induce the Gcn5p/SAGA-catalyzed acetylation of histones at genes important for growth, thereby enabling their rapid transcription and commitment to growth. Thus, acetyl-CoA functions as a carbon-source rheostat that signals the initiation of the cellular growth program by promoting the acetylation of histones specifically at growth genes. Display omitted ► A burst of acetyl-CoA production accompanies and triggers entry into growth ► SAGA dynamically acetylates its substrates in tune with acetyl-CoA levels ► SAGA is recruited to activate growth genes during growth ► Acetylated histones are highly enriched at growth genes, specifically during growth