Table of Contents Background, Summary and Discussion. Colloquium on transitional boundary layers in aeronautics; Background, summary and discussion (R.A.W.M. Henkes). Introduction. Preliminary measurements of the distribution of the velocity of a fluid in the immediate neighbourhood of a plane, smooth surface by J.M. Burgers and B.G. van der Hegge Zijnen - revisited and discussed (H.H. Fernholz). Flight testing of a Fokker 100 test aircraft with laminar flow glove (N. Voogt). Session 1: Tollmien-Schlichting Waves and Subsequent Instabilities. Three-dimensional instabilities in boundary layers (Y.S. Kachanov). Nonlinear development and breakdown of TS-waves in an adverse pressure gradient boundary layer (B.F.A. van Hest, H.F. Groenen, D.M. Passchier). Subharmonic K-regime of boundary-layer breakdown (S. Bake, Y.S. Kachanov, H.H. Fernholz). Investigation of active control of Tollmien-Schlichting waves on a wing (M. Baumann, W. Nitsche). DNS of boundary-layer instability and transition using the spatial approach (U. Rist). Direct numerical simulation of transitional separated fluid flow around a circular cylinder (V.A. Gushichin). Session 2: Cross-Flow Instabilities. Nonlinear stability, saturation, and transition in swept-wing flows (M.S. reibert et al.). Experimental investigation of cross-flow instability under the influence of controlled disturbance excitation (T. Lerche, H. Bippes). Direct Numerical Simulation of transition in a three-dimensional boundary layer (T. Wintergerste, L. Kleiser). Correlation between linear stability analysis and crossflow transition near an attachment line (C.J. Atkin. D.I.A. Poll). Proper orthogonal decomposition applied toboundary-layer transition on a swept wing (K.L. Chapman et al.). Session 3: Attachment-Line Instabilities. Numerical and experimental studies related to skin friction drag reduction problems (D. Arnal, J. Reneaux, G. Casalis). The effects of suction and blowing on stability and transition at a swept attachment line (D.I.A. Poll, M. Danks, M.R. Yardley). On secondary destabilisation of an attachment line boundary layer in compressible flow (V. Theofilis). Session 4: Applied Transition Analysis. Some introductory remarks on transition prediction methods based on linear stability theory (J.L. van Ingen). Some aspects of linear stability calculations in industrial applications (H.W. Stock, W. Haase). The role of Zarf in predicting transition in three-dimensional flows with the saddle-point method (T. Cebeci, H.H. Chen, E. Besnard). On the status of applied transition analysis (Th. Herbert). Session 5: Transition Modelling. Topics in industrial viscous flow calculations (P.R. Spalart). Modelling the transitional phanomena with statistical turbulence closure models (K. Hanjalić, I. Hadžić). Some recent developments in the linear combination model (R. Narasimha). Transition prediction with turbulence models (A.M. Savill). Transition zone predictions for rapidly varying flows.(W.J. Solomon, G.J. Walker, J.P. Gostelow). Session 6: Asymptotic Analysis. Combining theory and computations for transition (F.T. Smith). Solutions of the inviscid triple-deck equations (P.W. Duck). On the formation of spikes in the growing waves for a laminar boundary layer (V.A. Kazakov). Session 7: Disturbance Sources and Receptivity. Streaky structures in transition (P.H. Alfredsson, M. Matsubara). Effect of riblets on flow structures at laminar-turbulent transition (V.V. Kozlov, G.R. Grek). Direct simulation of the development of a local finite amplitude disturbance in a compressible boundary layer (E. Laurien). Receptivity to sound on a parabolic leading edge (T.C. Corke, O. Haddad). Experimental investigation of supersonic boundary-layer receptivity (N.V. Semionov, A.D. Kosinov, A.A. Maslov). Session 8: High-Speed Flows. Transition in flight at supersonic and hypersonic Mach numbers (A. Bertelrud, S. Graves). Blunt cone transition at hypersonic speeds: the transition reversal regime (M.A. Zanchetta, R. Hillier). Experimental investigation of instabilities in hypersonic laminar boundary layer flow (V. Wendt). Laminar-turbulent transition process of a supersonic boundary layer on a flat plate (A.D. Kostinov, N.V. Semionov, Yu.G. Yermolaev). Wall-temperature effects on transition in supersonic boundary layers investigated by direct numerical simulations (W. Eissler, H. Bestek). Author Index.