I think you asked a similar question previously, which i answered for you earlier today. Please drop me an e-mail if you can't find it / need clarification

txtDescription - is a TextBox control private const int DEF_HEIGHT = 40; using( Bitmap bmp = new Bitmap( 1, 1 ) ) { using( Graphics g = Graphics.FromImage( bmp ) ) { int iHeight = 0; // make a string a little bigger by adding "\r\nW" - this give us one line // of free space SizeF size = g.MeasureString( string.Join( "\r\n", txtDescription.Lines ) + "\r\nW", txtDescription.Font, txtDescription.Width ); iHeight += (int)( size.Height + 0.5 ); // max size if( iHeight > 200 ) { txtDescription.ScrollBars = ScrollBars.Vertical; iHeight = 200; } else { txtDescription.ScrollBars = ScrollBars.None; } // min size if( iHeight < DEF_HEIGHT ) iHeight = DEF_HEIGHT; this.Height = iHeight; } } } Good Luck Alex Kucherenko

Benjamin, Try the following: Initialise a local field, default to the usual height of the textbox: private int _InitialHeight = 20; In the constructor of the derived class: this.Multiline = true; this._InitialHeight = this.Height; Then override the OnTextChanged Method: protected override void OnTextChanged(System.EventArgs e) { //Get graphics System.Drawing.Graphics g = this.CreateGraphics(); //Get size System.Drawing.SizeF s = g.MeasureString(this.Text, this.Font); //Get the number of line (on top of the original 1), which need to be viewed int lines = Convert.ToInt32(s.Width) / this.Width; //Work out the height the control must be to view all lines int height = (lines * Convert.ToInt32(s.Height)) + this._InitialHeight; //Set height this.Height = height; } I hope this does what you need. Let me know if you'd like elaboration on any point. Note that this does not take into account the user using the enter key.