While there is ample evidence that individual monetary incentives increase worker effort when individual performance is measurable, comparable evidence for teams is scarce. We fill this gap by running a randomized experiment in a retail chain of roughly 200 shops. Our treatment, administered from April to June 2014 to shops selected through stratified randomization, was to offer a team bonus of up to 300 Euros per month for achieving sales beyond the target. The average treatment effect on sales is around 3%. The treatment effect is higher for the shops located in big towns (6%), historically underachieving their sales targets (5%), and with relatively young workforce (6%). The effect on the number of person-visits is similar in magnitude, and there was no difference to the availability of sales staff, suggesting that performance gains in the treatment shops were achieved through improved shopping experience. (Coauthors G. Friebel, M. Heinz, M. Krueger.)