1–aminocyclopropane–1–carboxylic acid is the immediate precursor for ethylene, a phytohormone that is produced in many plant tissues, which is effective in trace amounts (≤ 1 yl/l). Quantitative determination of ACC in biological tissues is paramount to understanding the regulation of this metabolic process. The most widely accepted method for quantifying 1–aminocyclopropane–1–carboxylic acid requires its oxidation to ethylene, which then is measured by gas chromatography. Our objective was to develop a method for the rapid, direct quantification of 1–aminocyclopropane–1–carboxylic acid by using a gas chromatograph with a flame–ionization detector. Ethylene production was measured in tissues from fruits, leaves, seeds, florets, and flower petals. The remaining tissue samples were ground to a fine powder in liquid nitrogen, and 1–aminocyclopropane–1–carboxylic acid was extracted from the powder with a methanol:chloroform:water mixture (5:12:3 v/v/v). 1– aminocyclopropane–1–carboxylic acid was quantified by using an EZ:faast^TM gas chromatography mass-spectrometry free amino acid analysis kit, was identified using gas chromatography mass–spectrometry, and was confirmed with authentic 1–aminocyclopropane–1–carboxylic acid. Additional benefits include a short run time of six minutes and the absence of a potentially hazardous tracer, such as ¹⁴C. We show that this method is effective for accurate, direct measurement of 1–aminocyclopropane–1–carboxylic acid from both reproductive and vegetative plant tissues.