This disclosure describes compositions, kits, methods, systems, and three- dimensional parts. According to an example, described herein is a threedimensional printing composition comprising: a polymeric powder build material comprising a thermoplastic polymer powder composition, wherein the thermoplastic polymer powder composition comprises: (a) at least 50 wt% of a C3 polyolefin, or a mixture of two or more polyolefins including at least 60 wt% of a C3 polyolefin based on the total weight of the mixture of the two or more polyolefins, (b) 0.1 to 1 wt% antioxidants, (c) 0.1 to 5 wt% flow aids, (d) 0-10 wt% of a surface modifying agent, (e) 0.05-wt%-10 wt% antistatic agents, (f) 2 wt% to 40 wt% filler, wherein the total of (a) to (f) is 100 wt%.