A two-part investigation was performed to study the relationship between defects formation and deformation characteristics in plane-strain side- pressing and axisymmetric plastic indentation. In the first part, the investigation was undertaken to examine the detailed deformation characteristics involved in axisymmetric plastic indentation. Circular punches with flat and hemispherical ends were indented into specimens prepared from SAE 1215 steels under as-received and annealed conditions. In the second part, the detailed mechanics of the side-pressing of circular cylinders under plane-strain conditions were obtained, based on the observed flow patterns of commercially pure aluminum and copper specimens. Slip-line fields and corresponding hodographs were constructed, and stress calculations were made, taking into account the actual material properties.