Summary: Many preachers and bible teachers assert that "the evidence" of the baptism with the Holy Spirit, in every instance, is speaking in tongues. This is correct. However, along with this every-time evidence of tongues, there are many additional results and evidences of the Spirit-filled life.
Acts 1:4-5; 2:1-4 ...  For John baptized with water, but in a few days you will be baptized with the Holy Spirit... [2:4] All of them were filled with the Holy Spirit and began to speak in other tongues as the Spirit enabled them.
• (1)Speaking in tongues - always! This is universally "the initial evidence" that a believer has been baptized with the Holy Spirit. The identical evidence of tongues occurred also in Acts 10:44-46 and Acts 19:1-6 when believers were filled with the Holy Spirit.
• But there are other results and evidences of the Spirit-filled life in addition to the every-time evidence of speaking in tongues. A Spirit-filled, tongues-speaking Christian should not stop at the experience of speaking in tongues. The Holy Spirit will also bring other spiritual manifestations into the daily expression of the Spirit-filled life.
• (2)“As the Spirit enabled them ... [KJV] gave them utterance” — To the Spirit-filled Christian there comes an enabling by the Spirit to do things not possible in the natural — for example, as here, the speaking of a language one has not learned.
• (4) “be [His] witnesses” — A Spirit-filled Christian grows in the ability to be an effective witness (for example, Peter's dynamic, soul-winning sermon on the Day of Pentecost [Acts 2]!).
Acts 2:14 Then Peter stood up with the Eleven, raised his voice and addressed the crowd: “Fellow Jews and all of you who live in Jerusalem, let me explain this to you; listen carefully to what I say.”
• (5)Fear is replaced by courage. Before Pentecost, Peter denied Christ three times. After Pentecost and his personal experience of the Pentecostal infilling of the Spirit, Peter preached boldly in Jerusalem.
Acts 2:16-17 No, this is what was spoken by the prophet Joel: “In the last days, God says, I will pour out my Spirit on all people. Your sons and daughters will prophesy your young men will see visions, your old men will dream dreams.”
• (6)Prophecy, visions, dreams, even among the young people, begin to be experienced by those living the Spirit-filled life.
Acts 2:36 "Therefore let all Israel be assured of this: God has made this Jesus, whom you crucified, both Lord and Christ."
• I can picture the suprised bible teachers and students reaching right now for their concordances. Please do; there you will find that never in the four Gospels is the full name — "Lord Jesus Christ" in any order of those three words — revealed. It is not disclosed until its revelation to Spirit-filled Peter in Acts 2:36!
Acts 2:41 Those who accepted his message were baptized, and about three thousand were added to their number that day.
• (8)Spirit-filled believers begin to see greater fruit in their ministries. Prior to Pentecost, the apostles had never borne fruit of this magnitude. Then here, on the very day of their Pentecostal baptism, Peter preached a sermon that won 3,000 converts to the Lord and to water baptism.
Acts 2:43 ...and many wonders and miraculous signs were done by the apostles.
• (9) Some Spirit-filled believers — not necessarily all — begin to be used in what have been called the “power gifts”.
Acts 3:6-7 Then Peter said, "Silver or gold I do not have, but what I have I give you. In the name of Jesus Christ of Nazareth, walk."  ...and instantly the man's feet and ankles became strong.
Acts 3:16; 4:10, 12 “By faith in the name of Jesus, this man whom you see and know was made strong. It is Jesus' name and the faith that comes through him that has given this complete healing to him, as you can all see.... [4:10] ...it is by the name of Jesus Christ...  Salvation is found in no one else..."
• (11) The baptism with the Holy Spirit makes you Christ-centered, not Holy-Spirit-centered. As Spirit-filled Paul said, "We preach Christ!" One of the Holy Spirit's works is to make us effective in pointing people to Jesus Christ.
Acts 4:29-31 Now, Lord, consider their threats and enable your servants to speak your word with great boldness... [31b] And they were all filled with the Holy Spirit and spoke the word of God boldly.
• I was baptized with the Holy Spirit, with the evidence of speaking in tongues, in Anchorage in 1971. Immediately I sensed a stronger prompting from God and a greater enablement to articulate God's Word to people.
Acts 6:2-5 ... choose seven men from among you who are known to be full of the Spirit and wisdom.... [5b] They chose Stephen, a man full of faith and of the Holy Spirit; also Philip [and 5 others]...
• (13) The original seven deacons — and all deacons then and now — can fulfill their serving ministries best when they are "full of the Spirit".
• Every ministry — deacons, elders, pastors, or any other — is most effectively accomplished in the fullness of and leading by the Holy Spirit.
Acts 8:29 The Spirit told Philip, "Go to that chariot and stay near it."
• (14) A remarkable result of the Spirit-filled life is the ability, as determined by God according to the need, to hear the Holy Spirit's voice directly.
• In Anchorage, Alaska, in the early 1970s, my wife and I were called in to pray for a woman in the throes of demon possession. For hours we prayed and invoked the Lord's Name, but without apparent victory. Then we stopped and asked the Lord for wisdom. I distinctly heard the Holy Spirit speak within me: "She thinks she has committed the unforgiveable sin!" I declared to her, by the Lord's Word, that she had not done this. Then, as we rebuked the devils once again, four of them came out of her. Within minutes the young woman became born again and filled the the Spirit, speaking in tongues and praising God. Our hearing a specific "word" from the Holy Spirit had illuminated the situation and given us the wisdom and direction to see the exorcism completed with great victory for her.
Acts 16:7 When they came to the border of Mysia, they tried to enter Bithynia, but the Spirit of Jesus would not allow them to.
• (15) Spirit-filled, Spirit-led Christians are sensitive to the Holy Spirit's prohibiting of ministry that may be man's sincere idea, but is not God's.
• I had a personal experience of this in 1971, when I was a new, Spirit-filled believer in a Pentecostal church in Anchorage, Alaska. I had gotten it into my mind that I should travel about the country in evangelistic ministry. I meant well; my heart wanted to serve God. But the Spirit of God, in a series of divine interventions, restrained me and revealed to me that His intent was that I stay there, learn and grow, then serve in the ministry of bible teaching. And, as one might expect, I quickly saw many proofs that the evangelistic ministry had been my idea, but that the bible teaching call was from the Holy Spirit. How gracious of Him to gently restrain me from following my sincere, but man-originated and erroneous, direction.
Ephesians 5:18-20 ...be filled with the Spirit.  Speak to one another with psalms, hymns and spiritual songs. Sing and make music in your heart to the Lord,  always giving thanks to God the Father for everything...
• (16) Spirit-filled believers will find their hearts stirred with music to the Lord. To be sullen and downcast is contrary to that which the Holy Spirit does in our hearts as we live the Spirit-filled life.
• (17) Finally, the Spirit-filled life will be characterized by a continual attitude of thankfulness to God.
If you find this topic interesting, may we recommend two related, more in-depth bible studies: