A basic unsolved question in cell biology is how the size of organelles is determined. Eukaryotic flagella (also known as cilia) are ideal organelles to study size control because they are linear structures and therefore require only a single number to specify size. Based on pulse-labeling and other experimental analyses, we have developed a simple model for flagellar length control based on the inherent length-dependence of intraflagellar transport. We compare the predicted dynamic behavior of the model, implemented by a series of increasingly complicated network implementations, with experimental observations of live cells. In order to further explore the functioning of this system, we have begun to measure biological noise in length control, and to couple experimental measurements of noise with predictions based on small-signal noise analysis of the model. These analyses allow us to deduce how mutations which affect length may change individual parameters within the model, as well as to predict novel phenotypes to be sought in future genetic screens. The approaches we are developing for studying flagellar length control should be applicable to other organelle size control problems.