| Operating System | Thread Library | |
| AIX 4.x | Native | |
| BSDI 2.x | MIT-pthreads | |
| BSDI 3.0/3.1 | Native | |
| DEC UNIX 4.x | Native | |
| DEC True64 Unix | Native | |
| FreeBSD 2.x | MIT-pthreads | |
| FreeBSD 3.x | Native | |
| HP-UX 10.20 | MIT-pthreads | |
| HP-UX 11 | Native | |
| Linux 2.0+ x86 | LinuxThreads | |
| Linux 2.0+ Sparc | LinuxThreads | |
| Linux 2.0+ MIPS | LinuxThreads | |
| Linux 2.0+ Alpha | LinuxThreads | |
| Linux 2.0+ PPC | LinuxThreads | |
| NetBSD 1.3 Intel | MIT-pthreads | |
| NetBSD 1.3 Alpha | MIT-pthreads | |
| OS/2 Warp 3 & 4 | Native | |
| OpenBSD 2.x | MIT-pthreads | |
| SCO OpenServer | FSU Pthreads | |
| SCO UnixWare 7.0.1 | Native | |
| SGI Irix 6.x | Native | |
| Solaris 2.5+ Sparc | Native | |
| Solaris 2.5+ X86 | Native | |
| SunOS 4.x | MIT-pthreads | |
| Win95, Win98 and NT | Native |
