Parallel Motion

create interest while melody is moving by harmonizing in parallel
thirds or sixths below the melody are normally most effective
switch between thirds and sixths below melody so chord tones predominate
technically, this produces similar or contrary motion
this technique often effective when the melody moves stepwise and in quarter notes
also effective for brief passages in eighths (especially parallel thirds)
switching between parallel thirds and sixths is also useful when melody leaps
the underlying voicing may often be simplified
try to make sure the third and seventh is present either in voicing or moving part
when parts move by step in parallel, color is inevitable
the change of texture is often welcome in itself

Jazz Piano Holiday