<h4 dir="auto">Code Sample, a copy-pastable example if possible</h4>
<div class="highlight highlight-source-python notranslate position-relative overflow-auto" dir="auto" data-snippet-clipboard-copy-content="df = pd.DataFrame( data = {
                         'acol'  : np.arange(4),
                         'bcol' :  2*np.arange(4)
                        })
df.drop(df.bcol &gt; 2, axis=0, inplace=True)

print(df)"><pre class="notranslate"><span class="pl-s1">df</span> <span class="pl-c1">=</span> <span class="pl-s1">pd</span>.<span class="pl-v">DataFrame</span>( <span class="pl-s1">data</span> <span class="pl-c1">=</span> {
                         <span class="pl-s">'acol'</span>  : <span class="pl-s1">np</span>.<span class="pl-en">arange</span>(<span class="pl-c1">4</span>),
                         <span class="pl-s">'bcol'</span> :  <span class="pl-c1">2</span><span class="pl-c1">*</span><span class="pl-s1">np</span>.<span class="pl-en">arange</span>(<span class="pl-c1">4</span>)
                        })
<span class="pl-s1">df</span>.<span class="pl-en">drop</span>(<span class="pl-s1">df</span>.<span class="pl-s1">bcol</span> <span class="pl-c1">&gt;</span> <span class="pl-c1">2</span>, <span class="pl-s1">axis</span><span class="pl-c1">=</span><span class="pl-c1">0</span>, <span class="pl-s1">inplace</span><span class="pl-c1">=</span><span class="pl-c1">True</span>)

<span class="pl-en">print</span>(<span class="pl-s1">df</span>)</pre></div>
<h4 dir="auto">Expected Output</h4>
<div class="highlight highlight-source-python notranslate position-relative overflow-auto" dir="auto" data-snippet-clipboard-copy-content="	acol	bcol
0	0	0
1	1	2"><pre class="notranslate">	<span class="pl-s1">acol</span>	<span class="pl-s1">bcol</span>
<span class="pl-c1">0</span>	<span class="pl-c1">0</span>	<span class="pl-c1">0</span>
<span class="pl-c1">1</span>	<span class="pl-c1">1</span>	<span class="pl-c1">2</span></pre></div>
<h4 dir="auto">Observed Output</h4>
<div class="highlight highlight-source-python notranslate position-relative overflow-auto" dir="auto" data-snippet-clipboard-copy-content="	acol	bcol
2	2	4
3	3	6
4	4	8
"><pre class="notranslate">	<span class="pl-s1">acol</span>	<span class="pl-s1">bcol</span>
<span class="pl-c1">2</span>	<span class="pl-c1">2</span>	<span class="pl-c1">4</span>
<span class="pl-c1">3</span>	<span class="pl-c1">3</span>	<span class="pl-c1">6</span>
<span class="pl-c1">4</span>	<span class="pl-c1">4</span>	<span class="pl-c1">8</span></pre></div>
<h4 dir="auto">Problem description</h4>
<p dir="auto">The anticipated behavior was that rows with <code class="notranslate">bcol</code> &gt; 2 would be dropped.  The actual behavior is that the boolean gets converted to 0/1, and then treated as index label.  So <em>row numbers</em> 0 and/or 1 are dropped... but all other rows will be kept.</p>
<p dir="auto">The documentation did not make it clear what was happening.</p>
<p dir="auto">Solutions might include documentation clarifying that <code class="notranslate">.drop()</code> cannot be used with boolean indexing, or a warning when receiving the (attempted) boolean index.</p>
<h4 dir="auto">Output of <code class="notranslate">pd.show_versions()</code></h4>
<details>
INSTALLED VERSIONS
------------------
commit: None
python: 3.6.1.final.0
python-bits: 64
OS: Linux
OS-release: 2.6.32-573.12.1.el6.x86_64
machine: x86_64
processor: x86_64
byteorder: little
LC_ALL: None
LANG: en_US.UTF-8
LOCALE: en_US.UTF-8
<p dir="auto">pandas: 0.20.2<br>
pytest: 3.1.2<br>
pip: 9.0.1<br>
setuptools: 33.1.1.post20170320<br>
Cython: 0.25.2<br>
numpy: 1.12.1<br>
scipy: 0.19.1<br>
xarray: 0.9.6<br>
IPython: 6.1.0<br>
sphinx: 1.6.3<br>
patsy: 0.4.1<br>
dateutil: 2.6.0<br>
pytz: 2017.2<br>
blosc: None<br>
bottleneck: 1.2.0<br>
tables: 3.4.2<br>
numexpr: 2.6.2<br>
feather: None<br>
matplotlib: 2.0.2<br>
openpyxl: 2.5.0a1<br>
xlrd: 1.0.0<br>
xlwt: 1.2.0<br>
xlsxwriter: 0.9.6<br>
lxml: 3.8.0<br>
bs4: 4.5.3<br>
html5lib: 0.9999999<br>
sqlalchemy: 1.1.11<br>
pymysql: 0.7.9.None<br>
psycopg2: 2.7.1 (dt dec pq3 ext lo64)<br>
jinja2: 2.9.5<br>
s3fs: 0.1.1<br>
pandas_gbq: None<br>
pandas_datareader: None</p>
</details>
<p dir="auto">Shouldn't this work?</p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="&gt;&gt;&gt; pd.version.version
'0.13.0-472-g9109812'

&gt;&gt;&gt; df = pd.DataFrame(np.random.random((10,4)))

&gt;&gt;&gt; df = df.drop(df[0] &gt; .5)

&gt;&gt;&gt; df.drop(df[0] &lt; .2)
---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)
&lt;ipython-input-23-5df7f56de272&gt; in &lt;module&gt;()
----&gt; 1 df.drop(df[0] &gt; .5)

/usr/local/lib/python2.7/dist-packages/pandas-0.13.0_472_g9109812-py2.7-linux-x86_64.egg/pandas/core/generic.pyc in drop(self, labels, axis, level, inplace, **kwargs)
   1397                 new_axis = axis.drop(labels, level=level)
   1398             else:
-&gt; 1399                 new_axis = axis.drop(labels)
   1400             dropped = self.reindex(**{axis_name: new_axis})
   1401             try:

/usr/local/lib/python2.7/dist-packages/pandas-0.13.0_472_g9109812-py2.7-linux-x86_64.egg/pandas/core/index.pyc in drop(self, labels)
   1621         mask = indexer == -1
   1622         if mask.any():
-&gt; 1623             raise ValueError('labels %s not contained in axis' % labels[mask])
   1624         return self.delete(indexer)
   1625 

ValueError: labels [False False  True  True  True  True  True False] not contained in axis"><pre class="notranslate"><code class="notranslate">&gt;&gt;&gt; pd.version.version
'0.13.0-472-g9109812'

&gt;&gt;&gt; df = pd.DataFrame(np.random.random((10,4)))

&gt;&gt;&gt; df = df.drop(df[0] &gt; .5)

&gt;&gt;&gt; df.drop(df[0] &lt; .2)
---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)
&lt;ipython-input-23-5df7f56de272&gt; in &lt;module&gt;()
----&gt; 1 df.drop(df[0] &gt; .5)

/usr/local/lib/python2.7/dist-packages/pandas-0.13.0_472_g9109812-py2.7-linux-x86_64.egg/pandas/core/generic.pyc in drop(self, labels, axis, level, inplace, **kwargs)
   1397                 new_axis = axis.drop(labels, level=level)
   1398             else:
-&gt; 1399                 new_axis = axis.drop(labels)
   1400             dropped = self.reindex(**{axis_name: new_axis})
   1401             try:

/usr/local/lib/python2.7/dist-packages/pandas-0.13.0_472_g9109812-py2.7-linux-x86_64.egg/pandas/core/index.pyc in drop(self, labels)
   1621         mask = indexer == -1
   1622         if mask.any():
-&gt; 1623             raise ValueError('labels %s not contained in axis' % labels[mask])
   1624         return self.delete(indexer)
   1625 

ValueError: labels [False False  True  True  True  True  True False] not contained in axis
</code></pre></div>