Spin bowling is a valuable skill in cricket, holding a place in the record books for its wicket taking abilities. The spin bowling technique is complex; however, the instruction of this skill has been largely formulated from the collective intuitions of past players. In addition, a standard model of bowling technique has been generally prescribed for both off‑spin and leg‑spin bowlers, with no biomechanics research validating this approach. Consequently, the understanding of spin bowling performance and technique have been largely left at an anecdotal level. In addition, it has not been validated that one basic action model is applicable for both off-spin and leg-spin. Therefore, the aim of this thesis was to explore the kinematics of spin bowlers to determine the differences in spin bowling performance and technique between off‑spin and leg‑spin bowling. Consequently, coaches and players can be provided with a clearer understanding of both the assessment and instruction of off‑spin and leg‑spin bowling, potentially allowing successful spin bowlers to be taught to perfect their skill. A review of scientific and coaching literature was performed to examine what is currently known about spin bowling performance and technique (Chapter 2). While there were a number of studies that have investigated particular aspects of spin bowling, there were evidently substantial gaps in the scientific literature. No study has performed a thorough analysis of the kinematics of spin bowling comparing off‑spin and leg‑spin techniques. Any potential differences in technique could have implications for the assessment and coaching of each spin bowling type. Furthermore, no study has investigated the segmental kinematics associated with generating ball spin. Coaching literature, as well as research performed in fast bowling and other similar motions, provided some suggestion for what may be found in spin bowling. In Chapter 3, the performance outcomes of spin bowlers were assessed using a three‑dimensional (3D) motion analysis of the spinning ball. The placement of three retro‑reflective markers on the ball’s surface allowed for the measurement of both linear and angular kinematics. Thirty‑four district‑level spin bowlers (twenty off‑spinners and thirteen leg‑spinners), delivered twenty standard deliveries, and five of any variation deliveries in their repertoire. Data were processed to calculate the ball’s linear speed, spin rate, and direction of the angular velocity vector, with respect to a right-handed bowler. The results show that spin bowlers can be categorised according to the horizontal component of the angular velocity vector (horizontal spin angle). The off‑spinners delivered with a negative horizontal spin angle, indicating a ball that would potentially deviate to the right after landing, while the leg‑spinners delivered with a positive horizontal spin angle, indicating a ball that would potentially deviate to the left after landing. In addition, the vertical component (vertical spin angle) was used to quantify the amount of swerve potentially produced by bowlers. It was found that leg-spin bowlers could deliver with either a positive or negative vertical spin angle, associated with swerve either towards the left or right, respectively. To determine the relationship between the contrasting spin directions and spin bowling technique, a comparison of the off‑spin and leg‑spin bowling techniques was performed (Chapter 4). The three‑dimensional (3D) kinematics of 23 off‑spin and 20 leg‑spin bowlers were measured. As suggested in the coaching literature, off‑spin bowlers had a significantly shorter stride length (p = 0.01) and lower spin rate (p < 0.01), but a greater release height than leg‑spinners (p = 0.01). However, the study found a number of other kinematic differences that were not documented in the coaching literature. The leg‑spinners were characterised by a larger rear knee flexion (p = 0.01), faster approach speed (p < 0.01), and flexing elbow action during the arm‑acceleration phase, compared with the off-spinners who extend the elbow more than 15°, which constitutes an illegal “throwing” action according to the ICC specifications for suspect bowling actions (International Cricket Council, 2015). Off‑spin and leg‑spin bowlers were also similar in a number of kinematic variables; however, some of these deviated from the standard coaching model such as a front‑on mixed bowling action, flexed front knee angle at release, and varying use forearm mechanics (Type‑1 and Type‑2). Chapter 5 identified the segmental kinematics of technique that were specifically associated with the main performance outcome, spin rate. Amongst the 23 off‑spin and 20 leg‑spin bowlers in the cohort, a large majority used a Type‑2 action (forearm rotation in the opposing direction to the direction of spin torque imparted on the ball). Therefore, an analysis of 3D segmental kinematics was determined from the Type‑2 bowlers: 15 leg‑spin and 20 off‑spin bowlers. Bivariate product‑moment correlation coefficients revealed a number of variables that were associated with spin rate. Type‑2 off‑spin bowling was associated to a greater extent with the timing of thorax movements, while Type‑2 leg‑spin bowling was associated to a greater extent with the pelvis rotation and pelvis‑shoulder separation movements. Rear hip flexion velocity differentiated between bowlers in both groups, in subtly different ways; the off‑spin technique was determined by the magnitude of the velocity, whereas the leg‑spin technique was determined by the timing of the velocity. Contrary to the standard coaching model, the rear hip flexion velocity occurred after the pelvis rotation. Generalised linear models identified the most critical variables. In the off‑spin group, the earlier occurrence of thorax anterior flexion maximum velocity accounted for 17.8% of the increase in spin rate, with an additional 1.9% accounted for by the rear hip flexion velocity. In the leg‑spin group, an earlier occurrence of the maximum rear hip flexion alone accounted for 32% of the variance in spin rate. The major differences between the variables identified in off‑spin and leg‑spin groups can potentially be attributed to the contrasting spin directions produced by each technique. The results of this thesis have implications for both the assessment and coaching of spin bowling. A clear methodology was established to measure any spin bowling delivery in the laboratory, determining its potential spin direction and swerve direction. Conceivable changes to coaching instructional manuals could be made, based on the findings of the kinematic studies. By understanding what aspects of technique are related to generating greater spin of the ball, coaching can be more effective, particularly when differentiating between off‑spin and leg‑spin as well as their respective Type‑1 and Type‑2 actions. Future research can expand on the studies performed in this thesis, repeating the analyses on different and more specific cohorts. For example, groups based on the forearm action (Type‑1 or Type‑2), front knee action (flexor or extender), as well as expanding to the elite level of bowlers. A more detailed analysis of the timing of segment rotations could provide a more specific understanding of the segmental sequencing profile in different types of spin bowling. Furthermore, a kinetic analysis could expand on the findings of this study, providing a deeper understanding for the mechanisms behind the kinematic differences.