that extends through the base and has a total length of about 54 inches preferably the strap extends from side portions 32 and from side portion 34 for a combined exposed length of at least about 18 inches more preferably at least about 24 inches to extend under the seat of a typical dining chair such as chair 100 strap 20 is wrapped around chair base 102 and fastened by locking quick release buckle 106 which is configured to permit tightening of strap 20 around chair base 106 strap 22 extends from side portions 70 72 fig1 for a preferred combined length of at least about 12 inches more preferably at least about 18 inches and is positioned around chair back 104 booster seat 10 is secured to chair 100 by fastening quick release buckle 108 and tightening strap 22 referring to fig5 child 200 is seated in booster seat 10 with safety strap 24 between legs 202 204 and around the abdomen 206 adjusting straps 92 not shown and 94 secures child 200 to booster seat 10 and raises the seating height of child 200 by at least the thickness of seat base 12 in one example child 200 weighs about 20 pounds and seat base 12 has a nominal thickness of at least about 1 inch while child 200 is seated thereupon.