Conservative Christian apologists want Acts of the Apostles (AoA) to be dated as early as possible. Looking at all of the evidence, however, indicates that AoA is a late 2nd century work. Here are some arguments for early dates and for later dates
Early Date for AoA
1. Doesn’t mention the death of Paul or Peter, which by tradition was around 64 CE
2. Reference to a “Theophilus” who was supposedly a High Priest in the 40s CE
3. Unfamiliar with and contradicts Paul’s letter to the Galatians
Later Date for AoA
1. Usage of Josephus (90s CE)
Josephus is the only known source to name Theudas. Additionally, he is named as an insurrectionist. The author of Acts makes a chronological mistake, “After him (Theudas) Judas the Galilean rose up.” But this mistake is based on the fact that Josephus mentions these two out of chronological order! The author of Acts is following the order of mention (Theudas then Judas) in Josephus Antiquities 10.5.1-2 without a careful reading of the context.
2. Glut of other ΠΡΑΞΕΣ (praxes – “acts”) type material in the 2nd century.
3. Theology similar to Polycarp (c. 125 CE) and the Pastoral Epistles
4. First witness to AoA and Pastoral Epistles is Irenaeus (c. 175 CE)
5. First witness to a collected Pauline epistle canon is Marcion (c. 140 CE), thus the first emphasis on the popularity of that apostle
6. Motivation to tame the elevated status of Marcion’s Paul and the elevated status of James to the Ebionites/Thomas
7. Written in third person, with unnatural transitions to first person plural (“we”) passages coinciding with sea voyages and unnatural transitions back to third person after sea voyages.
8. Theophilus was also the name of an eclectic Christian in the 2nd century (who I wrote about here) who seems to not know about the Jesus story.
Based on all of the internal and external evidences, I would conclude that AoA was written no earlier than Josephus and no later than Irenaeus. Dating it earlier than that seems to be based solely on apologetical grounds. It seems unreasonable that AoA would be written in the 40s or 60s CE and sit invisible and unused in Christian polemics until 110 – 130 years later. Also considering the unstable nature of papyrus used in the 1st century makes it even more unlikely that it would sit invisible without someone taking care of it (or copying it) to make sure it wasn’t destroyed.