Module Module1
    'You need to add references to Microsoft.Build.Framework and
    'Microsoft.Build.BuildEngine
    Sub Main()
        'Create a new Engine object
        Dim engine As New Engine()

        'Point to the correct path that contains the 2.0 clr/tools
        engine.BinPath = "c:\windows\microsoft.net\framework\v2.0.xxxxx"

        'Instantiate a new FileLogger to generate a build log
        Dim logger As New FileLogger()

        'Set logfile parameter to indicate the log destination
        logger.Parameters = "logfile=c:\temp\build.log"

        'Register the logger with the engine
        engine.RegisterLogger(logger)

        'Build the project file
        Dim success As Boolean = engine.BuildProjectFile("c:\temp\validate.proj")

        If success Then
            Console.WriteLine("Build successful")
        Else
            Console.WriteLine("Build failed - view the log")
        End If
    End Sub

End Module

using System;
using System.Collections.Generic;
using System.Text;
using Microsoft.Build.BuildEngine;

namespace BuildAProjectCS
{
    class Program
    {       
        static void Main(string[] args)
        {
            // Instantiate a new Engine object
            Engine engine = new Engine();

            // Point to the correct path that contains the 2.0 clr/tools
            engine.BinPath = @"c:\windows\microsoft.net\framework\v2.0.xxxxx";

            // Instantiate a new FileLogger to generate build log
            FileLogger logger = new FileLogger();

            // Set logfile parameter to indicate the log destination
            logger.Parameters = @"logfile=C:\temp\build.log";

            // Register the logger with the engine
            engine.RegisterLogger(logger);

            // Build a project file
            bool success = engine.BuildProjectFile(@"c:\temp\validate.proj");

            if (success)
                Console.WriteLine("Success!");
            else
                Console.WriteLine("Build failed - look at c:\temp\build.log for details");
        }
    }
}