There are provided methods and apparatus for constrained prediction for reduced resolution update mode and complexity scalability in video encoders and decoders. A scalable complexity video encoder includes an encoder for encoding a block in a particular picture in the video sequence by generating an intra mode prediction for the block using a constrained intra prediction process that reduces artifacts for both low and high resolutions in a reduced resolution update mode when the particular picture is eventually decoded. The constrained intra prediction process reduces the artifacts by prohibiting the use of particular prediction modes associated with the introduction of the artifacts in the reduced resolution update mode.