Beta oscillations observed in motor cortical local field potentials (LFPs) recorded on separate electrodes of a multi-electrode array have been shown to exhibit non-zero phase shifts that organize into planar waves. Here, we generalize this concept to additional classes of salient patterns that fully describe the spatial organization of beta oscillations. During a delayed reach-to-grasp task we distinguish planar, synchronized, random, circular, and radial phase patterns in monkey primary motor and dorsal premotor cortices. We observe that patterns correlate with the beta amplitude (envelope): Coherent planar/radial wave propagation accelerates with growing amplitude, and synchronized patterns are observed at largest amplitudes. In contrast, incoherent random or circular patterns are observed almost exclusively when beta is strongly attenuated. The occurrence probability of a particular pattern modulates with behavioral epochs in the same way as beta amplitude: Coherent patterns are more present during movement preparation where amplitudes are large, while incoherent phase patterns are dominant during movement execution where amplitudes are small. Thus, we uncover a trigonal link between the spatial arrangement of beta phases, beta amplitude, and behavior. Together with previous findings, we discuss predictions on the spatio-temporal organization of precisely coordinated spiking on the mesoscopic scale as a function of beta power. The local field potential (LFP) has long served as a readily available brain signal to monitor the average input activity that reaches the neurons in the vicinity of extracellular recording electrodes 1–3. A hallmark of the LFP is the ubiquitous presence of oscillations in various frequency bands 4 modulating in time and across different brain structures. These oscillations have been linked to a variety of brain processes such as attention 5 , stimulus encoding 6 , or memory formation 7,8. These findings support the basis of modern theories concerning the functional implication of oscillatory brain activities, such as feature binding 9 , the concept of communication-through-coherence 10–12 , the phase-of-firing coding 13 , or predictive coding 14. In motor cortex, beta oscillations (in the range of 15–35 Hz) are one of the most prominent types of oscillatory activity. They have been linked to states of general arousal, movement preparation, or postural maintenance 15,16 , and are typically suppressed during active movement 17,18. Technological progress recently led to the development of multi-electrode arrays enabling neuroscientists to record massively parallel neuronal signals in a precisely identifiable spatial arrangement. Although LFP signals recorded in motor cortex from electrodes separated by up to several millimeters are typically highly correlated 19 , the analysis of the instantaneous phase of the oscillation 20 revealed a non-zero temporal shift between electrodes 21. Such shifts may be expressed by the formation of dynamic spatial patterns propagating along preferred directions across the cortical surface, referred to as traveling waves 22. Indeed, the phenomenon of traveling waves has been described in multiple brain areas, such as the visual cortex 23–25 , including voltage sensitive dye recordings 26–30 , in the turtle visual cortex 31,32 , the olfactory bulb 33,34 , the thalamus 35 , and in visual perception 36 , and during epilepsy 37. While some studies reported waves in visual cortex as single-cycle propagation of elevated