The study aimed to develop a checklist and a rating scale version of the Leadership Potential Inventory for Adolescents (LPIA). Specifically, it sought to establish reliability and validity of these two versions of the Inventory. Cronbach’s coefficient alpha was applied for internal consistency (reliability). Three procedures were followed to validate the two versions. First, content validation for the LPIA item pool was undertaken by a test development expert with more than 30 years of experience in measurement. Second, factor analysis was performed to identify the underlying dimensions of the two versions of the Inventory. Finally, convergent validity of LPIA dimensions with ten factors of a standardized personality test associated with leadership was established using Pearson Product Moment Correlation coefficient. Six hundred seventy-one (n = 671) adolescents, ages 14 to 18 years, from 4 public and 4 private schools in Metro Manila (50.37% third year and 49.63% fourth year high school) participated in two stages of instrument development. After a review of literature on checklists and rating scales, and instruments measuring youth leadership, a Table of Specifications (TOS) was developed, with two parts, Personal Characteristics and Relational Skills. The TOS was the blueprint in writing 83 statements for the initial item pool, which was content validated by a measurement expert. The revised item pool was then presented in checklist and rating scale (“Very true of me” to “Not at all true of me”) formats, and administered to 432 high school students. Item and test statistics (Cronbach’s alpha) were used to select 35 items in the final versions. Two hundred thirty-nine adolescents responded to the final versions and the 16PF, a standardized personality test used for convergent validity. Both checklist and rating scale were found to be reliable, with Cronbach’s alpha of 0.84 for the checklist and 0.92 for the rating scale. The two parts, Personal Characteristics (k = 20) and Relational Skills (k = 15), also had high internal consistency, 0.74 and 0.73 respectively for the checklist, and the same value, 0.87, for the rating scale. Cronbach’s alpha was higher for the entire instrument, than for each of the two parts, whether it be the checklist or the rating scale version. This supports the theory that longer tests are more reliable than shorter ones. Reliability coefficients for the rating scale, whether for the entire scale (k = 35) and subparts, were higher than those for the checklist, confirming that instruments with interval scaling are more reliable than those using lower scaling levels. Among three factor analyses (2-, 3-, and 4-factor solutions) performed separately for the checklist and rating scale, the three-factor solution was chosen because it most coherently organized the items in the two versions of the instrument. These three factors were Logical Competence, Group Orientation, and Communication Skills, the three factors accounting for 28% of the variance in the checklist, and 41% in the rating scale. Convergent validity of the three dimensions of the LPIA checklist and rating scale versions was determined using Pearson product moment correlation coefficients computed between the three LPIA factor scores and ten 16PF factors associated with leadership. Correlation coefficients varied in strength, but all of them were significant at alpha level = 0.05. For the checklist version, the 16PF factors Reasoning, Perfectionism, and Sensitivity correlated highest significantly with LPIA factor Logical Competence; Self-reliance, Tension, Dominance, and Abstractedness with LPIA factor Group Orientation; and Emotional Stability, Liveliness, and Social Boldness with LPIA factor Communication Skills. For the rating scale, 16PF factors Self-reliance, Social Boldness, Tension, and Sensitivity correlated highest with Group Orientation; Emotional Stability, Liveliness, and Perfectionism with Communication Skills; and Reasoning, Dominance, and Abstractedness with Logical Competence. The study concludes that the checklist and rating scale versions of the LPIA both have internal consistency. Rating scale, however, is more reliable than the checklist, and the whole instrument has higher internal consistency than any of its parts. The study also defines Leadership Potential in terms of three dimensions, Logical Competence, Group Orientation, and Communication Skills. A good leader is one who possesses critical thought, ability to maintain unity in the group, and proficiency in verbal exchange. Finally the study confirmed convergent validity with ten factors associated with leadership in the standardized personality inventory.