Spatial organization in the step-pool structure of a 1.58 km long section of the Vogelbach, a steep mountain stream ( average channel bed slope 0.17 m/m) in the Alpthal basin, Switzerland, is analyzed to evaluate the extent of randomness in the occurrence of steps and to isolate the potential hydraulic and topographic controls on step placement. Statistics of the observed step sequence are compared with those of random sequences generated by permutation from the observed step height distribution. Hydraulic and topographic controls on step placement are analyzed from step length and steepness distributions and relations between mean step properties and step height and channel gradient for both observed and random sequences. Results show that ( 1) observed step length distributions are statistically significantly different from randomly generated sequences, ( 2) step steepness is significantly different in observed data because of a positive correlation between mean step length and height and it remains fairly constant for all step sizes, ( 3) spatial organization in steps does not extend far beyond the nearest step, and ( 4) the influence of channel gradient on step properties is insignificant and highly variable, indicating that hydraulic rather than topographic controls are dominant for step placement in this stream. Although the Vogelbach is a steep stream on the boundary between a cascading and step-pool morphology where we would expect randomness to dominate, spatial organization was nevertheless detected in many important aspects of the step-pool geometry.