We present and interpret Global Positioning System (GPS) measurements of crustal motions for the period 1988-1997 at 189 sites extending east-west from the Caucasus mountains to the Adriatic Sea and north-south from the southern edge of the Eurasian plate to the northern edge of the African plate. Sites on the northern Arabian platform move 18 +/- 2 mm/yr at N25 degrees +/- 5 degrees W relative to Eurasia, less than the NUVEL-1A circuit closure rate (25 +/- 1 mm/yr at N21 degrees +/- 7 degrees W). Preliminary motion estimates (1994-1997) for stations located in Egypt on the northeastern part of Africa show northward motion at 5-6 +/- 2 mm/yr, also slower than NUVEL-1A estimates (10 +/- 1 mm/yr at N2 degrees +/- 4 degrees E). Eastern Turkey is characterized by distributed deformation, while central Turkey is characterized by coherent plate motion (internal deformation of <2 mm/yr) involving westward displacement and counterclockwise rotation of the Anatolian plate. The Anatolian plate is de-coupled from Eurasia along the right-lateral, strike-slip North Anatolian fault (NAF). We derive a best fitting Euler vector for Anatolia-Eurasia motion of 30.7 degrees +/- 0.8 degrees N, 32.6 degrees +/- 0.4 degrees E, 1.2 degrees +/- 0.1 degrees/Myr. The Euler vector gives an upper bound for NAF slip rate of 24 +/- 1 mm/yr. We determine a preliminary GPS Arabia-Anatolia Euler vector of 32.9 degrees +/- 1.2 degrees N, 40.3 degrees +/- 1.1 degrees E, 0.8 degrees +/- 0.2 degrees/Myr and an upper bound on left-lateral slip on the East Anatolian fault (EAF) of 9 +/- 1 mm/yr. The central, and southern Aegean is characterized by coherent motion (internal deformation of <2 mm/yr) toward the SW at 30 +/- 1 mm/yr relative to Eurasia. Stations in the SE aegean deviate significantly from the overall motion of the southern Aegean, showing increasing velocities toward the trench and reaching 10 +/- 1 mm/yr relative to the southern Aegean as a whole.