This commentary analyses Article 9.1.4 of the UNIDROIT Principles of International Commercial Contracts (PICC) concerning partial assignment. Art 9.1.4 recognizes the economic need for assigning part of a right. Taking into account the underlying rationale of Section 9.1 of the PICC that the assignment should not burden the obligor, Art 9.1.4 draws a distinction between a right to the payment of a monetary sum and a right to other performance. According to this provision, a right to the payment of a monetary sum may be assigned partially. A right to other performance may be assigned partially only if it is divisible, and the assignment does not render the obligation significantly more burdensome. This commentary discusses the right to the payment of a monetary sum, right to other performance, the divisibility of a right, the additional burden that a partial assignment may put on the obligor, and the effects of partial assignment on the obligee and obligor.