Planning the management for a patient with recurrent patellar instability should be based on information gained from a thorough history and physical examination and supplemented with relevant radiological investigations. In taking the history it is important to distinguish between pain and instability and an open mind should be kept regarding the source of instability symptoms. Recurrent episodes should be distinguished from a single event and the initial episode should be well understood, particularly in relation to the degree of trauma involved and the response of the knee. Symptoms in the other knee and in other family members suggest the presence of predisposing factors. Important components of the physical examination include static and dynamic alignment, a general knee examination, and assessment of patellar height, mobility, and apprehension, as well as patellar tracking. An assessment of femoral version and tibial torsion should be made. The radiological assessment of patellar instability continues to evolve. Although plain radiographs, computerized tomography, and magnetic resonance imaging are all used, a good-quality lateral radiograph with the knee in 20°-30° flexion provides information about the 2 most important factors — patellar height and trochlear dysplasia. The importance and role of the tibial tuberosity-trochlear groove distance has been questioned in recent research. If surgery is undertaken it should be tailored to the specific needs of the individual patient. No universally accepted algorithm exists for the planning of surgery. There appears to be a trend to use medial patellofemoral ligament reconstruction as the mainstay of surgery with an apparent reduction in the use of medial tibial tuberosity transfer. Additional procedures, particularly tibial tuberosity distalization and — in some centers — trochleoplasty, can be used to address predisposing factors that are felt to be significant contributors to the patient’s problem. Procedures may need to be modified in the skeletally immature or individuals with hyperlaxity. Femoral and tibial osteotomies may have a role in habitual and permanent patellar dislocation.