Rhythm in music performance commonly requires transitions between different subdivisions of the beat. Such transitions are generally regarded as attention demanding and prone to error. It is therefore interesting to ask: Are there changes in timing in advance of the transition reflecting preparation and are there adjustments are made after the transition? In my talk I will present results from two studies (carried out with A Semjen and R Balasubramaniam) in which 8 musically trained participants switched between a basic beat (1200 ms) and subdivisions of 2, 3 and 4 either with or without a metronome. Study I included 4 conditions: fixed interval tapping without any switch (BAS), tapping with one switch to one of the four subdivisions (HOM), alternation between the basic beat and one subdivision (ALT) and switching between various subdivisions (MIX). The various conditions revealed greater absolute error and greater variability with more transitions. There were changes in interval timing immediately before and after each transition with tapping slowed before and variability elevated after. Study II included just ALT and MIX conditions but with longer periods between transitions to better characterize return to pretransition performance levels. Similar results were obtained to Study I. But, in addition, an analysis of the form of movement was performed. This showed changes in the relative duration of flexion and extension around the transition point. Taken together these studies show the complex sharing of motor and timing processes in a timing task of some relevance to music performance. I will discuss implications for theories of timing and movement control.