diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..dbec55f
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+*.sw[op]
diff --git a/lib/sudoku_board.rb b/lib/sudoku_board.rb
new file mode 100644
index 0000000..b597f77
--- /dev/null
+++ b/lib/sudoku_board.rb
@@ -0,0 +1,66 @@
+class SudokuBoard
+  attr_reader :board
+
+  def initialize(game_file)
+    @board = []
+    File.readlines(game_file).each do |line|
+      row = convert_line_to_row(line)
+      @board << row unless row.nil?
+    end
+  end
+
+  def [] (row, col)
+    @board[row-1][col-1]
+  end
+
+  def []= (row, col, value)
+    @board[row-1][col-1] = value
+  end
+
+  def row(row)
+    @board[row-1]
+  end
+
+  def col(col)
+    column = []
+    @board.each { |row| column << row[col-1] }
+    column
+  end
+
+  def sub_grid(number)
+    # SubGrids are numbered 1-9 like this:
+    #   1,2,3
+    #   4,5,6
+    #   7,8.9
+    row, col = sub_grid_start(number)
+    s_grid = []
+    3.times do
+      s_grid += sub_grid_row(row,col)
+      row += 1
+    end
+    s_grid
+  end
+
+  def sub_grid_row(row,col)
+    [self[row,col],self[row,col+1],self[row,col+2]]
+  end
+
+  def convert_line_to_row(line)
+    line.chomp!.delete!('-+| ')
+    return nil if line.empty?
+    line.tr!('.','0')
+    row = []
+    line.each_char.map { |c| row << c.to_i }
+    row
+  end
+
+  def sub_grid_start(sub_grid)
+    row = ((sub_grid-1)/3)*3 + 1
+    col = ((sub_grid-1)%3)*3 + 1
+    [row,col]
+  end
+
+  def missing_data?
+    !(self.board.flatten.index( 0 )).nil?
+  end
+end
diff --git a/lib/sudoku_validator.rb b/lib/sudoku_validator.rb
new file mode 100644
index 0000000..69b400a
--- /dev/null
+++ b/lib/sudoku_validator.rb
@@ -0,0 +1,72 @@
+require_relative './sudoku_board'
+
+class SudokuValidator
+  attr_reader :board, :errors
+
+  def initialize(game_file)
+    @game_file = game_file
+    @board = SudokuBoard.new @game_file
+    @errors = []
+  end
+
+  def validate
+    status = check_game_status
+    validity = check_game_validity
+    [validity, status]
+  end
+
+  def check_game_status
+    @board.missing_data? ?  'incomplete' : 'complete'
+  end
+
+  def check_game_validity
+    rows_valid = check_row_validity
+    cols_valid = check_col_validity
+    subgrids_valid = check_subgrid_validity
+    (rows_valid && cols_valid && subgrids_valid) ? 'valid' : 'invalid'
+  end
+
+  def check_row_validity
+    valid_element?(:row)
+  end
+
+  def check_col_validity
+    valid_element?(:col)
+  end
+  
+  def check_subgrid_validity
+    valid_element?(:sub_grid)
+  end
+
+  def valid_element?(element)
+    item_valid = true
+    (1..9).each do |item|
+      valid, error = valid?(@board.__send__(element,item))
+      item_valid &&= valid
+      report_errors(error, element, item)
+    end
+    item_valid
+  end
+
+  def valid?(ary)
+    tmp = ary.map { |e| e if e !=0}.compact
+    valid = tmp.uniq.size == tmp.size
+    error = []
+    error = identify_errors(tmp) if !valid
+    [valid,error]
+  end
+
+  def identify_errors (ary)
+    tmp = ary.clone
+    error = []
+    while tmp.size > 0 do
+      item = tmp.shift
+      error << item if tmp.include? item
+    end
+    error
+  end
+
+  def report_errors (ary,where,item)
+    ary.each { |e| @errors << "#{e} is repeated in #{where} #{item}" }
+  end
+end
diff --git a/spec/sudoku_board_spec.rb b/spec/sudoku_board_spec.rb
new file mode 100644
index 0000000..599dafe
--- /dev/null
+++ b/spec/sudoku_board_spec.rb
@@ -0,0 +1,64 @@
+require_relative '../lib/sudoku_board'
+
+describe SudokuBoard do
+  before do
+    @game_vc = SudokuBoard.new("valid_complete.sudoku")
+    @game_ii = SudokuBoard.new("invalid_incomplete.sudoku")
+  end
+
+  describe "#[]" do
+    it "returns the first character of the sudoku file" do
+      expect(@game_vc[1,1]).to eql 8
+    end
+
+    it "returns an arbitrary element from the board" do
+      expect(@game_vc[4,5]).to eql 4
+    end
+    
+    it "returns zero for an empty position" do
+      expect(@game_ii[2,4]).to eql 0 
+    end
+  end
+
+  describe "#row" do
+    it "returns the first row of the sudoku file" do
+      expect(@game_vc.row(1)).to eql [8,5,9,6,1,2,4,3,7]
+    end
+    
+    it "returns the expected row" do
+      expect(@game_ii.row(4)).to eql [0,0,0,1,0,7,0,0,2]
+    end
+  end
+
+  describe "#col" do
+    it "returns the first column of the sudoku file" do
+      expect(@game_vc.col(1)).to eql [8,7,1,9,3,2,4,6,5]
+    end
+    
+    it "returns the expected column" do
+      expect(@game_ii.col(8)).to eql [0,0,0,0,0,0,7,0,4]
+    end
+  end
+
+  describe "#sub_grid" do
+    it "returns a 3x3 sub-grid as an array" do
+      expect(@game_vc.sub_grid(1)).to eql [8,5,9,7,2,3,1,6,4]
+    end
+
+    it "returns a middle 3x3 sub-grid" do
+      expect(@game_vc.sub_grid(5)).to eql [1,4,7,2,6,8,5,9,3]
+    end
+
+    it "successfully returns the last sub-grid" do
+     expect(@game_vc.sub_grid(9)).to eql [6,7,5,8,9,3,2,4,1] 
+    end
+
+    it "successfully returns the first sub-grid" do
+      expect(@game_vc.sub_grid(1)).to eql [8,5,9,7,2,3,1,6,4]
+    end
+
+    it "returns the expected sub-grid" do
+      expect(@game_ii.sub_grid(8)).to eql [0,8,0,0,0,0,0,3,6]
+    end
+  end
+end
diff --git a/spec/sudoku_validator_spec.rb b/spec/sudoku_validator_spec.rb
new file mode 100644
index 0000000..5faff15
--- /dev/null
+++ b/spec/sudoku_validator_spec.rb
@@ -0,0 +1,70 @@
+require_relative '../lib/sudoku_validator'
+require_relative '../lib/sudoku_board'
+
+describe SudokuValidator do
+
+  describe "valid games" do
+    it "correctly recognizes a valid, complete game" do
+      result = %x{"./sudoku_validator" "./valid_complete.sudoku"}
+      expect(result).to eq "This sudoku is valid, and complete.\n"
+    end
+
+    it "recognizes a valid, incomplete game" do
+      result = `./sudoku_validator ./valid_incomplete.sudoku`
+      expect(result).to eq "This sudoku is valid, and incomplete.\n"
+    end
+  end
+
+  describe "invalid games" do
+    it "recognizes an invalid, complete game" do
+      result = `./sudoku_validator ./invalid_complete.sudoku`
+      expect(result).to include "This sudoku is invalid, and complete.\n"
+      expect(result).to include "2 is repeated in col 6"
+    end
+  end
+
+  describe "error handling" do
+    before do
+      @game = SudokuValidator.new "./invalid_complete.sudoku"
+      @element = [1,2,3,2,5,6,7,8,9]
+    end
+
+    it "identifies correct element in #identify_errors" do
+      expect(@game.identify_errors @element).to eql [2]
+    end
+
+    it "returns errors in #valid?" do
+      expect(@game.valid?(@element)).to eq [false, [2]]
+    end
+
+    it "returns empty error array in #vaid? if no errors" do
+      @element[3]=4
+      expect(@game.valid?(@element)).to eq [true, []]
+    end
+
+    it "returns the descriptive error string for col errors" do
+      @game.validate
+      @game.errors.should include "2 is repeated in col 6"
+    end
+
+    it "returns the descriptive error string for row errors" do
+      @game.board[1,1] = 7
+      @game.validate
+      @game.errors.should include "7 is repeated in row 1"
+    end
+
+    it "returns the descrptive error string for sub-grid errors" do
+      @game.board[1,1] = 7
+      @game.validate
+      @game.errors.should include "7 is repeated in sub_grid 1"
+    end
+
+    it "ignores missing (zero) elements for incomplete sudokus" do
+      @game.board[1,1] = 0 
+      @game.board[1,7] = 0
+      @game.board[1,4] = 0
+      @game.validate
+      @game.errors.should_not include "0 is repeated in row 1"
+    end
+  end
+end
diff --git a/sudoku_validator b/sudoku_validator
new file mode 100755
index 0000000..e42d569
--- /dev/null
+++ b/sudoku_validator
@@ -0,0 +1,7 @@
+#!/usr/bin/env ruby
+require_relative 'lib/sudoku_validator'
+
+@validator = SudokuValidator.new(ARGV[0])
+validity, status = @validator.validate
+puts "This sudoku is #{validity}, and #{status}."
+@validator.errors.each { |err| puts err }