To whom addressed? “… to write out for you in consecutive order, most excellent Theophilus” (Luke 1:3) “The first account I composed, Theophilus …” (Acts 1:1)
Continuity of action “He parted from them and was carried up into heaven” (Luke 24:51) “The first account … until the day when He was taken up” (Acts 1:2)
Continuity of promise “I am sending forth the promise of my Father upon you; but you are to stay in the city …” (Luke 24:49) “He commanded them not to leave Jerusalem, but to wait for what the Father had promised” (Acts 1:4)