Abstract Background The coach-coachee working alliance and coachee motivation seem important factors for achieving positive coaching results. Self-determination theory, specifically basic psychological need theory, has been proposed as a relevant framework for understanding these relationships. The current longitudinal survey study therefore investigates prospective associations between coachees’ appraisal of the working alliance, basic psychological need satisfaction, and the coaching outcome indicators goal attainment, wellbeing, absence of psychopathology, and personal growth initiative. Methods The sample (N = 181) consisted of Dutch coachees that were recruited across a range of coaching settings and contexts. Online self-report questionnaires were administered twice (T0 and T1), with an intervening time of 3 weeks, assessing working alliance, basic psychological need satisfaction, goal attainment, wellbeing, absence of psychopathology, and personal growth initiative. Parallel analysis with Monte Carlo ...